failed at 1, you cannot create a gmail account with a VPN (unless you want to verify by phone)
Perhaps simplest of all, you could always sign up for the email on a semi/public wifi access point, or even from a shared computer, as from an internet cafe or even a friends phone.
The most likely option to use is residential proxies which are real IPs of devices, these are very hard to block but expensive.
Probably best to just go to a public wifi and used a burner phone if that’s what you want to do.
A lot of services that I don't want then to have my PII are starting to ask for phone verification.
Though I don't know if they are somehow blacklisted by Google. And the main service is just a one time verification rental but you can also rent a number for a few days.
Instead of writing this comment you could've taken one of the nodes you run (since you seem to be so qualified) and simply install openvpn on it and connect to it. Then go and visit sites that would be restrictive, or visit any site that tells you more about your IP.
But sure, go off and question my qualifications because you haven't considered this, or tried it, or ran into the issue yourself.
Plus, the way Discord, for example, does phone numbers, is that they just block anything they arent quite sure about.
I know that I have difficulties using some services because I cannot afford faster internet, for example.
I definitely did that in past.