Enforcement in practice is almost certain to be "at the edge" with things like payment processors and ad networks that have direct business operations in the EU and are easy to demand third-party compliance from.
If you literally don't do any business with EU entities, even at arm's length, enforcement is going to be impractical and unlikely.
I also believe this. If you run a side project by yourself and you don't target EU users directly, but might have a few, it most likely won't be worth the effort to actually follow through on enforcement.
However, that seems like a very arbitrary line and governments love to waste money.
If you literally don't do any business with EU entities, even at arm's length, enforcement is going to be impractical and unlikely.