How would they even do that? A VPN is just a remote machine. Anything can be a VPN
I don’t think that will stop them trying though
- drop wireguard / OpenVPN packets crossing the country border
- analyze https traffic to detect traffic patterns not matching https fully and block such connectionsEDIT: I might be confusing vless/xray/reality but seems like there are no problems to block it based on ip reputation + tls fingerprint + amount of connections https://habr.com/ru/articles/1044396/
Of course this would block some valid websites but when has government cared about that
If you are willing to block browsing all ordinary web sites fronted with a CDN, then yes you can block reality/xhttp. You cannot, however, differentially block it via any of the three things you mentioned.
The government (any government) hates its citizens and the freedoms it had to allow them