I used nginx for multiple web servers on a single public IP but...

Now I have a different problem, I'd like to make a multisite with different subdomains, like test.domain test1.domain all referencing to the same website hosted on the root "domain", while maintaining the subdomain on the web browser and possibly with some way to limit access, e.g.:

• test.domain can access resource "/pippo" as "test.domain/pippo" but test1 can't as "test1.domain/pippo"
• test, test1 and root can access "/login" thus permitting "shared" access.

Does all of this have sense or is it better to do 3 different sites hosted separately, with separate logins, data ecc.?

Rn I'm using CLOUDFLARE pages, so I aim to be serverless using their service, GitHub and SvelteKit.