ERPNext is now under “deconstruction” … . Frappe developers are splitting it in different aplications. Until v14, apps like payments, hrms, education, etc … was part of the monolyth ERPNext.
I don’t know any official list of apps, except MarketPlace (Frappe Cloud Marketplace) . Here you’ll find a lot of applications … some of this apps require ERPNext, and others just need Frappe …
Also relying on apps for production system isn’t something I’d recommend.
Apps aren’t maintained for current ERPNext version. If you rely on app heavily and it doesn’t get support for latest version you can’t upgrade.
A lot of app in the list you can see only support ver 12 or 13.