I moved over to Proton from Google because I liked the idea of having an alias for each service. After two months and a Mail Plus trial, I now pay for Proton Unlimited. I use Mail (due to alias linking), Calendar, and Pass often. I don’t really use VPN that much (although it is useful sometimes), and Drive is just too slow. I didn’t have any issues with Google, and I liked using Gmail and Calendar. Proton also doesn’t have watch apps, so I have to add my calendars through iCal to Google Calendar for my watch. It feels to me like I’m just overpaying now. Should I move back to Google for mail and calendar? I’m probably going to keep Pass (it seems just a bit too expensive compared to Bitwarden, though).
You can pay less than $1/month for domain (i.e. on Porkbun or Cloudflare) and have unlimited email forwarding for services. Just set up catch all and forward that to your Proton/Gmail. And your own domain might be useful for you in future.