I frequently encounter people asking about moving from Gmail but I never understand, please help me understand if I'm wrong. Doesn't Gmail still let you forward emails to a 3rd party address? In which case just sign up for another email service and you're done. Email is a standard, not a service. I've changed email addresses probably about as many times as years I've been alive, it's probably the least likely service I could think of that you could be tied in to. Am I missing something huge here?

Never had gmail, I used my ancient hotmail to signup for a google account.

In addition to the other advice given in this thread, set an autoreply in your gmail that telld you that you have switched email addresses and include your new address. This way, people know of your new email address if someone still manages to mail you on your old email address.

make periodic backups of your gmail account content on your own computer(s) and setup auto responder on gmail to use a new email address; easy peasy

I started by having my gmail forward to an alias email that goes to a newer more privacy focused email.

From there I would just update account when I got an email from them or the next time I used an account. It is slower then just going through all your accounts on your password manager, but its less daunting and typically the accounts you use the most are going to get updated quickly anyway.

At this point my gmail functions as a "professional sounding" alias for when I am not going to bust out my phone to create an alias for something I am doing in person.

As for something like gdrive, best practice is to have more then one backup, and encrypt what you put on cloud servers to avoid any scanning issues.