Buying Another Domain for Email Forwarding Service

I own a custom domain for my main email provider so if I switch to a new one I won't have to change all my address for contacting people. I am considering buy a separate domain for just my email forwarding service.

What do people on here do?

Current Setup:

domain1.com - for main email

alias.domain1.com - for email forwarding with Addy.io

New Option:

domain1.com - for main email

domain2.com - for email forwarding with Addy.io

Cross posted from: https://lemmy.blahaj.zone/post/34446665