It's likely easiest on GitHub Codespaces, as I have configured a working environment.
Simply do:
cd DotNet
dotnet publish
This will create:
bin/Release/net8.0/linux-bionic-arm64/publish/libdotnet.so
bin/Release/net8.0/linux-bionic-arm64/publish/libdotnet.so.dbg
And copy to:
Native/app/src/main/libs/arm64-v8a/