MeanMrMustard
The simplest method is open Element app, create new account and just use the matrix home server for your ID. You can search other servers for a more federated ID if you like.
Make whatever name you want to use for your MatrixID. It will ask for an email to send a confirmation link. I'm not sure what other ID confirmation from another device is.
But your accounts aren't linked between this forum and Matrix. I apologize for mentioning Matrix, that's just what I've used. Discord may be easier to use if you like. I have nothing to do with either platform, it's up to what you want to use