Technically yes but I've played with onion services only on raspberryPi. I'd rather separate such things from my Bitcoin node.
With subdomains yes. So same onion like page1.
Could customize over clearnet with a reverse proxy like Im doing with mine. Example:
Pay.sdbitcoiners.com
Thanks. I don't know how to do a reverse proxy yet. It's something I've always wanted to learn.
Here's a guide. I changed it to add other services but works well as is for btcpay.
https://docs.btcpayserver.org/Deployment/ReverseProxyToTor/#reverse-proxy-to-tor
WIth Start9 Pages service yyou can put different web pages on different subdomain of the same Tor URL. In StartOS 040, Pages will support different Tor URLs for different sites as well as clearnet domain hosting
