I’ve made this recommendation before, but buy your own domain. It’s cheap, and will allow you to change your email hosting provider should Fastmail pivot their business from email to surveillance.
It’s pretty easy to set up. Others have offered, and I’ll repeat it: if you need a hand getting started, I’ll help.
EDIT: Fastmail’s instructions https://www.fastmail.com/help/receive/domains.html
Still, the only 100% secure way to do it.
You can of course set up all sorts of monitoring, but then you have to check that that is working. These concerns never really go away. You cannot truly let your email slip from your mind, because if it stops working ever you will miss emails (unless you use a relay, which is either external or also needs monitoring, etc) and that means that potentially things get closed that should not be closed, you miss things from the doctor/dentist, etc.
I like protonmail enough to buy their first tier email hosting, which gives this ability.
And, if I find a better email hosting service, or roll my own, my email doesn't change, of course.
I get people wanting to use less Google services, but why quit all together?
We keep a few hundred GB of family photos and videos in Apple Photos/iCloud. You could also consider Flickr now that they're owned by SmugMug