Tailscale requires each person be granted access, I.e. it's private. (Edit:I didn't know about Tailscale Funnel, which is more like Cloudflare tunnel)
Cloudflare Tunnel gives anyone on the internet access, but to my knowledge only covers HTTP traffic. If what you're trying to do requires port numbers then I don't think that will work.
In regards to media traffic, Cloudflare silently removed that section of their Ts & Cs, so hosting Jellyfin, etc should now be OK.
You might be able to use Tailscale on a cheap VPN to forward traffic to your setup, but it might be cheaper and easier to pay your ISP.
It's worth pointing out that port forwarding happens on your router, but if you don't have a public IP then it won't work. Sometimes ISPs will give you a public IP if you just ask, sometimes they tie it to a static IP add-on and charge for it. It sounds like you might be in the latter case. It can vary by ISP, so if you live somewhere where you get a choice, you may find another ISP is a better deal (e.g. where I live some charge $15 a month for a static IP, some charge a one off $40 fee, and some you can just ask and they will give you a public dynamic IP for free. Others will give everyone public dynamic IPs).