You can just run your own email server, considering the steps you have outlined here. Or at least use protonmail. Other anon email services already exist.
Also, why use Chrome? I stopped using Chrome for everything over a year ago, and Im kinda late to that party.
Running your own mail server requires registration and many potential surface attacks for being hacked and doxxed, a certain female political figure has been an example. Email servers are not secure, have you heard of Yahoo mail over 1 billion users that were hacked?
Have you ever run an email server?
Chrome is the best for extensions and if you're going to entrust large value, you should make sure it's solid and will not have issues
You would know this by the many reported problems with Firefox and Brave browser
If you read the whole thread, I've mentioned the purpose of the thread is to protect against the vast majority of adversaries but there are levels to security
This thread will not protect you if you become a target by state actors or a well capitalized team of hackers, nor should you worry about those threats if your crypto assets value is less than $1M
If you hold more, then go hire a team of security specialists to design a solution for you