This already exists, though of the browser see you doing it on a forbidden context it won’t even come as far as displaying the permission request popup.
That is really not accurate. It is fully compatible with HTML export AND can be used with multiple hosting platforms. For example, if you host your game on netlify, then it will work flawlessly. I’d have to check but I think it also works on gamejolt. I do not think it is fair to say that the HTML5 platform as a whole is unsupported just because two hosting providers are blocking all clipboard accesses from the games.
Note that this is not a rule of P2P: the ID is to be defined by the broker server. If you use a broker server of your own, you can make it generate IDs in whatever way you want, for example with a short word or shorter amount of numbers.
Alternatively, you could use the Text Entry object to allow selecting and copying the text as they would on other apps. That is also more intuitive and gives a sense of control to the player. Same for pasting in: just let the user paste it into a text entry. Since that is fully controlled by the user and not an unconditional permanent full-time read-write access to the clipboard, it is not restricted by the browser.
The ID system is not a limitation of GDevelop that can be avoided some day, it’s a core concept of peer to peer communication. You need to tell who you are sending a message to in some way, the machine can’t automagically guess that. If you want a friend’s system where you can search people through their usernames, find their ID this way or something… Well that’s already possible, using for example firebase (many have done so in the past), but that’s up to you to build, it’s not a problem that a networking feature is supposed to tackle.
If you are talking about the THNK Framework, as of now it only supports P2P as a backed and still requires a P2P ID to connect through it. Other networking features also will require some kind of identification of what server you are connecting to - whether a server name, IP address, or something else.