Someone else is having the same problem here: Tailscale Serve an already https port
I tried it myself and it seems if you try to serve a local HTTPS service over funnel, then the website can’t be reached.
So it seems that you currently can’t do that.
If your local network is a trusted environment then you could serve Homeassistant, etc. on HTTP within your LAN, and then use tailscale serve to serve them via HTTPS.
That way you can access these services via HTTPS inside your LAN and optionally expose some of them to the internet via tailscale funnel.
The only downside is that the CN of your HTTPS certificates will always be the FQDN of your tailnet node, e.g. yourmachine.yourtailnet.ts.net. Though with browser’s suggestions from history, local short-link services (e.g. golink by tailscale) and similar, that is not really an inconvenient downside IMO.