So we're on the same page: using WiFi in the usual way, by connecting to an Access Point via its SSID and an optional password, is not required to use ESP-Now. However, because ESP-Now requires that all peers are on the same channel, it's a convenient way to achieve that.
ESP-Now itself is "connection-less": you send directly to a given MAC or MACs; or do a broadcast to everything in range.
I can corroborate that if you call WiFi.begin for whatever reason, if you later want ESP-Now to work, you may have to call WiFi.disconnect first. Otherwise, things would start to flake then fail. This was an issue on a project of mine; turned out disconnecting was not going to be an issue, so fine. Didn't spend more time trying to figure it out. (This was on v2 of the esp32 board core, though; v3 has been out for a while now.)
If you want to run something like that tutorial with both ESP-Now and "regular" WiFi, then that would be a problem.