Looks like this was released ~Sept 2025 so early days for a custom ROM.
Re your link, that issue is on the subject of “Kernel Sources” which is one part of the issue for development. The last post seems to report released. Good.
Anticipating a ROM, is the bootloader unlockable?
Someone working on a Lineage or other AOSP build would at some stage produce a device tree and maybe put it online. A search like “Device tree + piano” might find such starting point. I found none yet in a quick search.
I see that it does fit the search I suggested but this is still limited to kernel. (However dropping these sort of links to “request a device” can be useful.)
Generic System Images (do search that too) can be a way forward for non supported devices.