I. GSI: Sure, it is worth a try. Especially if GSI is based on Lineage. The device does not have A/B as far as I remember, for example this version encoding suggests avN image should be enough - however only avS is provided there (with superuser). Maybe it is not a problem.
II. Other thing is that we still donât have complete logs to diagnose what is actually the error with your current system.img maybe it is unrelated. I know at least of one feature that would not work without Lineage, and that is fingerprint, but it should not block boot (and may not even work on toco at all). And FOD may not work with GSI either
III. And as last point, even if a build is not available, with a decent hardware one can imagine you can build one of the Lineage 17.1 for toco system images yourself, provided that there are sources out there (+ manifest entries).