I am considering getting a foldable now, or slightly later when they mature a bit, and I would like to put a custom ROM with a better-privacy or at the very least a FOSS community driven OS, which ROM’s exist currently that is tailored towards foldables, also I have a heavy preference to ROMS that take advantage of a Foldables physical features (fingerprint reader), or side-by-side view, and other things.
Why?
If you are refering to the recent news about Google moving away from public release in favor of licensed OEM manufacturer this has been over misinterpreted and debunk by GrapheneOS team.
GrapheneOS said that the whole OEM stuff only makes them slower at releasing major update for now (A16) and that they are in discussion with some OEM manufacturers to get a license on their behalf and supporting their hardware.