If you have your own domain name for your email, you can point it at any host's servers. Google in the case of Gsuite or Fastmail or Pobox or anyone else.

If you have regular backups, all you have to do is change a DNS record to switch to a different provider and you shouldn't lose any email in the process.

This is what I and many others do. I have had the same email address for ~20 years and have had it hosted on at least a half dozen providers over that time with no loss in data.

not the person you're responding to, but I have G Suite and I have my domain pointed at Google for mail. If for some reason Google came down hard on me, I could login to Namecheap and setup email to be handled by another provider (Microsoft, ProtonMail, whoever). So if someone emailed me at my email address, the only gap I risk is between the last time I read my emails and when I setup the new provider. Added bonus, "forgot password" on various sites will continue to work at this stage and I don't have to mass email people that my email address is now name@domain.tld.