As someone who was both an avid user of Therian Amino and a former administrator, it wasn't uncommon to see many of the newcomers ask for tips on their quadrobics or request a chatroom to be made in dedication to the exercise itself. Needless to say, quadrobics definitely wasn't unheard of over there.
I believe it can be a great exercise for someone to practice when possible, as as I see it, there's a good amount of benefits from it. Not only does it incorporate the usage of multiple parts of the body into the overall experience, but it also can be a great way to act out on instincts to drop down on all fours and move about as one's theriotype would.
Tiktok definitely has a good sum of quadrobic videos amassed, though so does Instagram and YouTube if you dig deep enough. There was a trend going around in the equestrian community, of which that still goes on today, around 2014 to 2016 or so where kids would post videos to their instagram page of them jumping as horses do in the arena. At the time there wasn't a link to therianthropy or anything along those lines with these posts, it was really a matter of being
that horse kid at the barn lol.
All in all, I see quadrobics as a pretty positive exercise to check out and see how it may benefit the individual in question