Yeah, ok. I just found this app when googling around for a way to control my MacBook Pro 16" M1 system volume from my iPhone.
I've been an Apple user since 1982, Mac user since the Mac IIcx. I must be on my 15th or 20th Mac by now. I've looked at 1000's upon 1000's of Mac apps good and bad across the years.
I downloaded BTT remote on my Mac, plus the companion app for my iPhone, skipped reading any instructions at all, and within 6 minutes had my problem solved.
I was blown away by how comprehensive, powerful, & well-designed the app is. It's like the remote-control version of Peter N Lewis's "Keyboard Maestro."
Bought a lifetime license -- maybe $22 is plenty for you but if you're not making a decent enough living, definitely increase the price.
Thanks & keep up the good work.