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).
Why not use Firefox Relay? It’s a mail forwarding service with 5 aliases in the free version, and unlimited in paid. I’m using that in combination with my gmail account and it works beautifully.
If you only occasionally need a vpn, the free tier in proton is probably sufficient (but you can’t select servers, they will be assigned at random), and you could use windscribe as a backup (you can select servers in the free tier yourself, but traffic is limited to 10GB per 30 days).
I liked Windscribe so much I ended up paying for it. With a discount code I found the price to be reasonable.