I also believe it’s possible to set up HTTPS encryption without a domain name, but it might result in that “we can’t verify the authenticity of this website” warning in web browsers due to using a self-signed certificate.

Just create your own rootCA and IntermediateCA and sign your certificate with those, put the CA in your trust store of your system and get rid of this self-signed warning on every device and happily access all your service via: *.home.lab or whater ever local domain pleases you.