vbmeta you can get from here https://ecloud.global/s/z2Tpgez8FfacnaQ
and GSI is only a system.img.
The vbmeta is for disable verified boot. The needed command I can give you when back at home
The vendor. partition has to stay original.
Here you will find everything I’m using [HOWTO] install eOS GSI on a Treble device