Personal email on custom domain?

I recently realised how dependant I am on my Google account and how f***** I'd be if I lost access to it, so I started diversifying a bit.

One of the ideas I had is creating my email account on my custom domain. In my home country I bought the domain lastname.tld and in my country's top level registrar pointed the name servers to Infomaniak and on Infomaniak I bought just the DNS Zone service for 1 euro that allows setting the DNS records for email.

I bought a paid Proton account, so I connected the email with my domain, so I now have an email address firstname@lastname.tld through Proton.

It works so far (just did it a few days ago), but the only thing that is an issue is that the emails sent from it may be going to spam (e.g. I tried to send an email to my wife on Gmail).

My idea behind this is that if I use my own domain I can never be locked out of my email permanently, e.g. if Proton locks my account I can move my domain somewhere else and will still be able to receive important emails.

What do you ​​think of this setup? Any suggestions on what can be done better?