So far I haven’t noticed any limitations, but I only use it infrequently (at most once or twice a week to watch an episode or two of a show together).

So YMMV, not sure how much you typically stream. I guess you could always have the other person manually set a lower quality so less data is being sent if you run into issues. The price of them not installing Tailscale!

Something I do is use a Tailscale Funnel to share a regular link with friends and family and it works well, without them needing an account.