It’s an Unisoc Tiger T610-based device:
https://www.devicespecifications.com/en/model/b51a591d
Seems that almost nothing needed is available to build…
…anyway here’s a -maybe- useful (re)source we found:
https://github.com/realme-kernel-opensource/realme_C31_C35_narzo50A-Prime-AndroidR-kernel-source
Anyway, since it’s shipped with Android 11, it should be a treble-enabled device and you can go wit GSI builds: