Unfortunately, no. For running grpc-dotnet, you need to be on the
ASP.NET Core stack, i.e. on .NET Core 3+ (or even .NET Core 2+ has just went out of support a few days ago).
Realistically, the Grpc.Core package will remain available for quite a while after that (we're not going to actively hide/remove it), but it won't be getting official support past the deprecation date.
Can .NET 5 and .NET 6 (where grpc-dotnet is fully supported) help you with migrating off of .NET Framework?
Btw, if this is about the needing to run on older windows versions (that don't have .NET Core or .NET 5+, preinstalled), please note that with .NET 5+ you can build standalone single-file deployments, which remove the need to pre-install stuff on machines where you're are deploying.