I don't get the point of telling this story with out the rights.
Honestly, I think it can be done. There's tons of potential plot inferred in what's written, and what's in the notes they do have the rights to. Even if you decide to go with extremeish time dialation, there's a good story here to be told. As mentioned, you can infer certain events and let the known lore fill in the gaps. You can lay the Valinor groundwork without explicitly saying shit that you're not supposed (we know this because they tried to it, but just did it poorly and retconned shit because Amazon)
Here's a super rough, time dialated set of plot points that could be woven into (everything here is canon or super close enough to canon for hollywood, other than timeline, which is nuked from orbit) a coherent story that if told right would probably be fucking excellent.
- Sauron shows up in Lindon in disguise as a super handsome elf (Annatar) who claims to be an emissary from the West. Galadriel, Elrond, GG are skeptical because wise but the elves of Eregion (led by Celebrimbor) do buy it because they really really want to do shit as good as Feanor did. (can't say his name, but he's Celebrimbor's grandfather, so we can infer some shit and talk about Celebrimbor's bloodline being talented but greedy and hot headed about the desire to make great objects) and this guy has spectacular talent and knowledge he's willing to teach. Sauron & Celebrimbor become besties. Celebrimbor and Galadriel were kin and very close friends, she warns him about Annatar...oooh, dramatic tension. Celebrimbor and Sauron do their thing, Sauron tries to turn Celebrimbor against Galadriel & GG (there will later be a rebellion, this is building to that)
- Galadriel and Celeborn have a sneaky suspicion there is a Maia influencing M.E and set off searching to find it. If you want to depict Galadriel as a badass, here's your chance. She's her husbands boss, she has both elf magic and is handy in a scrap. Lots of room for adventure, drama, gorgeous vista set pieces. Everything you could want to make M.E feel huge, magical, gorgeous. Have her go to the numenorean settlements on the coast (largely populated with those faithful to the elves), meet Elendil, do some warning and foreshadowing (Galadriel smart/wise) start introducing faithful vs black numenoreans (call them dark instead of black because 2022) to foreshadow the downfall, numenorean politics, etc. After leaving Eregion (last chance to talk sense into Celembrimbor), Galadriel passed through Khazadum (we meet Durins folk) because something important...but Celeborn doesn't go (dwarves killed his Uncle in the first age, King Thingol, downfall of Doriath) and they separate dramatically/angrily (relationship drama!). That shit actually happened if we shift some names around (she didn't actually meet Elendil, but did warn a numenorean king who came to M.E to meet with her). Season ends with Celeborn riding away with a bunch of their party, and Galadriel entering the kingdom under the mountain with a sweet, cinematic khazadum reveal. Pure Tolkien magesty is her final scene of the season.
- Want wizards, proto hobbits and Lotr callbacks/foreshadowing? Sure, let's fucking get it. Wizard falls from sky. No need to play bullshit "is he sauron" game (because we already know sexy Annatar is just creepy sexy enough to be evil) but we're going to play "is he gandalf"? Proto hobbit finds comet wizard, in like EP2. Relationship build as proto frodo nurses comet wizard back to health. At end of EP4 there is action beat, barely sentient comet wizard saves the proto hobbits and his memories start to come back because used power...not completely because can't have comet wizard be OP until we need him to be in season finale. Comet wizard feels compelled to journey to Rhun for reasons he can't explain (2nd comet Wizard we'll meet later...these are of course the 2 blue wizards of the Istari that fuck all is written about so you have so much flexibility here) Comet wizard makes joke about his robes being grey and how Olorin would be upset with him for that...boom...revealed that he's not Gandalf. Off to Rhun the 2 not hobbits go with Blue Gandalf because that's what hobbits do. They walk extremely long distances, often in pairs, because wizards told them to. They can be pursued by weirdo sauron cult of dark magic users for drama (Hobbits do their best work while being chased by scary shit, here's your fleeing from the Shire call back), but let's not make them look like eminem in drag this time. Blue comet gandalf appears to sacrifice himself in season finale (gandalf callback/foreshadow) and says the name of who the hobbits need to find as he, I don't know, tumbles off of a fucking cliff with not eminem in drag.
- Elendil arrives back in Numenor after meeting Galadriel and being warned about a dark force rising. Finds Numenor changed since he left, gets caught up in Numenor high politics. Elendil finds plot to overthrow King (Pharazon is your baddie here)....high political intrigue (people love that shit...HOD sends it's regards) and is arrested in the season finale for treason, which they are totally threatening to kill him for. The beauty here is that in Tolkien's notes and writings on Numenor, very little other than the major plot points are explicit. Lots of wiggle room for made up shit here that as long as it's good, becomes defacto canon.
There. All canon or really close. Not a single fat shit taken on the rights to other properties in Tolkien's universe that you were too cheap to pay for, lots of cliffhangers (one literally) for your finale, lots of meaningful action beats, lots of lore and PJ callbacks/foreshadowing. Your series is being hailed as the heir to PJ's trilogy. All characters true to what is known about them at this time. No SauronGuy & Angry not really Galadriel sexy time story undertones. No silly "who is Sauron" forced mysteries. No re writes of material Tolkien was already kind enough to leave you.