If they’re blocking Wireguard/OpenVPN at the protocol level, there may not be anything you can do (running on a different port, etc).
If HTTPS works, between a cloud VPS and your home connection, you might be able to setup Nginx + VPN-WS on your cloud host to make a websocket-based VPN.
I haven’t tried this, but it looks solid enough. Just make sure you configure Nginx correctly for authentication since it doesn’t do that on its own (intentionally since most web servers already have a solid authentication framework / plugin system).
You may also try SSH port forwarding. Basically your home device maintains a persistent connection to the cloud server over SSH and forwards one or more ports (its SSH, for example) over that, and the cloud server makes that available.