Firefox’s free VPN will offer 50 gigabytes of monthly data, which is pretty generous for a browser-based VPN. A Mozilla account is required to make use of it, which isn’t a hardship (they’re free), but is a point of friction some may wish to know upfront.
They don’t know the URL but they know the IP address so … yes, they also can get the URL
IP addresses do not map to URLs.
They might map to domains, but not necessarily.
You cannot reliably get the URL from an IP, there’s no direct mapping, especially with shared hosting.