Do you use anything other than gmail?
I set my Gmail to forward to Proton when I switched, and gradually replaced the address in all my accounts and told friends and family to no longer use it. It took about a year but now everything goes to my custom domain. You don’t need Proton to do any of that, though. If you want to still reply from your Gmail and don’t care about encryption, Fastmail may be a better fit (although IMO it’s less of a good value compared to all the extras you get with Proton Unlimited)
Either way, I really can’t recommend a custom domain enough. I actually used Fastmail for a year before switching to Proton and it was completely painless thanks to the domain.
Whoa. If anyone else s wondering like I was how the hell this works, it’s basically a ZIP file that appears as HTML: https://github.com/gildas-lormeau/Polyglot-HTML-ZIP-PNG