GS6 is a different Chipset. It’s easy if: same vendor/OEM (Gigaset), same SoC, vendor is GPL release-happy and there is a dev that owns the device and cares.
.. it’s actually easier than prior generations of MTK. [..] modern MTK BSPs have a pretty clear delineation as to what’s GPL and releasable [..] ATM there’s a single header in G99 tree that links to vendor/mediatek [..]
Motorola is a vendor that releases sources early and has Mediatek devices. That’s why you can find more MTKs at LineageOS now
I looked up GS6 vs GX30 where it’s different (MediaTek Dimensity 6400). Anyway, Periphery (Camera, Screen, lots of sensors) is another thing. If you’re lucky Murena sells it, but until then a device needs to land in a motivated developer that requests sources and ports it.
as said, you can very likely use a GSI on any modern Android today. There’s less reasons to do individual ports when the periphery works with a GSI too (needs people to find out).
When one finds such devices one needs to search for the device codename [HOWTO] Find device codename if one hopes to find devs with an interest in building a LineageOS custom build …
or else follow the (non device specific) GSI route.