You don't have to do it all in one go. It isn't like you have to move everything all at once like you're moving to a new apartment.
I started moving away from gmail years ago. It took probably like 5-10 minutes to set up email under my own DNS control and to set a forwarding address on gmail that pointed to that email.
I didn't even bother to do an initial bulk move of things over to the new email, I just switched things over individually as needed in a sort of on-demand fashion. 30-60 seconds here and there moving over individual accounts one at a time and only when it became obvious that I was moving over something worth keeping up on.
Spread out like that it felt like almost no effort at all.
It's probably not even several hours of work for me, except that I do want to set that time aside in case something goes wrong and I need to revert things; I can't afford to not receive email anymore.
That, and I do want to transfer all my existing email history.
Every time google did something to piss me off I moved an account or two in anger. It felt good. It felt so good that when I searched my gmail and only found google-related hits in my password manager, I was slightly disappointed lol
(Don't get me wrong, I still want to do it, but it's still daunting.)