Making an item only register if another mod is present 1.20.1

I've been wanting to make an item that will only be registered if another mod is detected to be present. I was looking at older posts (primarily this one) and realize that this method most likely won't work anymore as it seems the items aren't registered from within the item's java and I worry that the code requirements have also changed.

If anyone knows how to work with this for 1.20.1 I would really appreciate some help!^^