Hey MBA, sorry but this forum is only for the Wurst Client, not for other hacked clients.
With that said, Wurst does usually work with Sinytra Connector so you should be able to get that to work in NeoForge 1.21.1. Just be aware that Forgified Fabric API for 1.21.1 is currently still stuck on version 0.107.0, which is very old and not compatible with the latest Wurst version. This means you'll need to use older versions of Wurst and of any other mods you plan to use. Here is a thread where someone found a working combination of Wurst and Sodium.
Hope this helps!
