Oh, it is not a smooth mechanism at all. If it were, everyone would use it. Google started to develop a browser extension some years ago to make key management and encrypting easier but it was abandoned because it would inhibit their ability to do targeted advertising.
Here is a link to set up PGP on Windows.
Thunderbird has PGP built in and it's pretty seamless once it's set up.
PGP is great. If you learn how to use it on your own device, it doesn't matter what host you use. If you post your OS, I'll can point you to instructions on setting it up locally.
You're never going to get the bulk of senders (library, town council, your aging parents) to encrypt their mail to you. Can you make peace with that?
It is important to find a host that has a funding model based on subscriptions instead of monetizing users.
My recommendation is find a host with a good subscription model and in a county that respects user privacy. I like KolabNow in Switzerland.
Start by looking at Hail and Shizuku. Both are FOSS and available to download from FDroid. Hail will allow you to freeze/disable the app. Shizuku will give you the appropriate permissions to do so.
I'm not surprised they got rid of it.
Link to their blog announcing it.