thxstr does anyone know if the coverage of the smaller front displays works as well [with GOS] as the respective vendors
Xiaomi, Samsung, and Motorola phones are not compatible with GOS at all.
It must be a Pixel to work at all with GrapheneOS, specifically one of these:
https://grapheneos.org/faq#supported-devices
From that link:
The expectation is for people to buy a secure device meeting our requirements to run GrapheneOS.
You can read up more at the link and elsewhere about why only Pixels are secure enough for the project's standards.