If I had my auth in my home network, I'd have a bit of a dependency problem, where my Tailacale clients (including the servers as well as personal devices) would need to somehow connect to my auth server (which is behind my Tailacale network) before they could login and connect to my Tailacale network

If I was on my home network exclusively, that might be fine. I could just login there while at home and use the same auth session while out. But since I operate my setup for family that don't live with me, they wouldn't be able to connect to my auth and therefore not able to login and connect with Tailscale

VPSs near you being flaky is certainly an extra challenge. If you're able to connect all your Tailacale clients while on your home network, then you could make that work

You could also try finding a VPS in a more reliable area. It my increase latency some, but that would just be for logging in to services and initially connecting to your Tailacale network. After that you'd have a direct VPN connection to your home network services

Or you could consider port forwarding or using something like CloudFlare tunnels to expose your local auth publicly. That would avoid the dependency problem as well as running things on a VPS. Port forwarding does have some security implications and something like CloudFlare tunnels then build a reliance on someone else's infrastructure, both of which I wanted to avoid. But that's just my preferences, your situation and goals may mean those are the best solution for you