I tried to build it from source following the steps in "Development Setup" readme and during step "Run dotnet restore" I got errors that (error NU1101) that packages with IDs "BepInEx.AssemblyPublicizer.MSBuild", "Microsoft.NETFramework.ReferenceAssemblies" and "HarmonyX" cannot be found.
Probably you have set up this package source as a default in the past and forgot about it (it is not there by default in a fresh visual studio 2022 + .net SDK installation, I added it in visual studio options), so it works for you.
So, I would suggest either adding that to the "Development Setup" or into NuGet.Config.
I tried to build it from source following the steps in "Development Setup" readme and during step "Run dotnet restore" I got errors that (error NU1101) that packages with IDs "BepInEx.AssemblyPublicizer.MSBuild", "Microsoft.NETFramework.ReferenceAssemblies" and "HarmonyX" cannot be found.
After some googling, I found that the problem is that package source Nuget.org (https://api.nuget.org/v3/index.json) knows these packages, but BepInEx (https://nuget.bepinex.dev/v3/index.json) for some reason doesn't.
Probably you have set up this package source as a default in the past and forgot about it (it is not there by default in a fresh visual studio 2022 + .net SDK installation, I added it in visual studio options), so it works for you.
So, I would suggest either adding that to the "Development Setup" or into NuGet.Config.