I have a home server and I have some HTTP services running on it. I'm thinking if I should even bother with HTTPS, as I'm already using tail scale which should be peer-to-peer and encrypted. So I shouldn't worry about any men in the middle.
Your VPN provides the former but not the latter. That said the odds of there being an issue in this regard are so slim as to be zero, so you'll probably be fine.
It can still have issues with potential attacks that would redirect your client to a system outside of the VPN. It would prevent MitM but not complete replacement.
Do you have any devices on your local network where the firmware hasn't been updated in the last 12 month? The answer to that is surprisingly frequently yes, because "smart device" companies are laughably bad about device security. My intercom runs some ancient Linux kernel, my frigging washing machine could be connected to WiFi and the box that controls my roller shutters hasn't gotten an update sind 2018.
Not everyone has those and one could isolate those in VLANs and use other measures, but in this day and age "my local home network is 100% secure" is far from a safe assumption.
Heck, even your router might be vulnerable...
Adding HTTPS is just another layer in your defense in depth. How many layers you are willing to put up with is up to you, but it's definitely not overkill.
You would still be using http on whatever network you're on while outside of the house. If you're on hotel or a friend's wifi, the data between you and tailscale would be clear text.
I might have misunderstood you, but data transferred inside the tailnet will always be encrypted by Tailscale.
So if you're connected to a public wifi and someone's looking at your traffic, accessing a random http site would be clear text, but accessing an http site inside your tailnet will be encrypted.
Unless you define an exit node and tell Tailscale to use it. And then all your traffic will be encrypted from the view of the one looking at your traffic logs from the public wifi (and clear text from the exit node to the random http site).
Yes, I misread and immediately deleted my post lol. I think you were talking about tailscale VPN, and I was thinking something more like cloudflare tunnel.
That said, the risk is still there that tailscale (or whichever middle company) can read your plaintext packets.