Gmail is an email service. Like the fediverse, email is federated.
By changing your email provider, do you really lose anything? You can still contact your friends, contacts and even various customer suports. You also can recieve emails from popular social media apps. If you degoogle from atleast one Google app, maybe Gmail could be the easiest and least life changing one.
While, Youtube could easilly be one of the most difficult to degoogle from. Not like literally but emotionally. Like deep down you know you can find mostly all you might need on something like Peertube but not all the entertainment media like on Youtube. You will also become a social outcast if peertube is the only app you use. You might not understand channels people mention in day to day talk from youtube or references.
If you use exclusively fediverse apps and sites, Chrome could be almost just as easy to replace as gmail, longterm. However If you use Youtube it won't surprise me that Youtube downgrades your performance and user experience in what ever means neccesary on competing browsers.
I've been using fastmail for a few months now. Besides being a really top-notch replacement for gmail and even adding a few features, it also onboards you by giving you a couple quick fields to fill out and then immediately imports everything you had in gmail. And then it keeps importing it, continuously, as long as you want.
It's not like i'm paying for gmail, so I'll keep the account alive as long as I need while I switch all the same accounts and records that you are (validly) mentioning as a barrier. I could actually do most of it in one sweep, if I just searched for my old email address in 1password, but it's not really that time-sensitive to switch, and in the meantime I get to use fastmail.