WWF is deprecated n my opinion. It hasn't received any updates in years. It is not on the roadmap for .NET 5 and future .NET versions. You can continue to use and develop with it of course because it is part of .NET Framework and therefore will not be removed. However since .NET 5+ is where everything is going you'll end up at some point having to migrate it (say 10 years from now). WCF server was in the same boat but enough people used it that MS made it open source. It is possible that they will do the same for WWF but I don't think it got as much use.
My personal recommendation would be to look for an alternative workflow engine.