You are going to need a domain name and a reverse proxy. But to be honest of you are asking that kind of question means you should not make your instance public and advertise it to the world just yet.

Learn how to secure your infrastructure and how everything is working together first.

Then you can check out what a reverse proxy is and what it is used for.

Only then you can open your instance to the public with whatever services you'd like. But remember, opening it to the outside without any security knowledge is asking for trouble

As diminou mentioned, do your research before you go down this road. You can also open yourself to DMCA takedowns if you aren't careful.

See: https://docs.invidious.io/hide-instance-behind-proxy-server/

It would be better for you to just run a private instance initially. You can use tailscale if you want to be able to access it remotely. That's the safest way to start out.

Edit: There's a tutorial here if you are intent on doing it: https://fedfree.org/docs/http/arch-invidious.html