I've recently recorded technical case study that goes through whole BTCPay setup... that can be used to host multiple merchants.

nostr:note1a4fxsswej4c3ng708vt60d2j5e55mkauxxtfya0wy0l9wtpm5glq5rmhtc

See if that guide works for you; I also highly recommend videos by @BTCsessions

https://www.youtube.com/watch?v=KqsM-n-e4aY

And then @Voltage has nice BTCPay guides as well:

https://www.youtube.com/watch?v=F-2tDH9J-_s 

 Beautiful. Appreciate it brother 

 There is also this beautiful step by step guide on minibolt: 
https://v2.minibolt.info/bonus-guides/bitcoin/btcpay-server