Well, both Flarum and Waterhole are written in Laravel, but honestly learning to tweak Laravel is no harder than learning to tweak XF - both are still just PHP under the hood.
I think the Waterhole dev thinks of it as “a forum framework” than “a forum application” and a lot of effort has gone into making specific areas specifically extensible, in a way that XF maybe doesn’t (at least not overtly), and it is at least in part geared to being able to be added into existing Laravel apps which is a different beast entirely compared to XF.
It is free for a local demo (which does contain all the functionality but is tied to a non public domain) so maybe give that a go?