Apps are fine. It's an entry point and some people might feel uncomfortable driving to a strange place to sit with strangers doing a strange activity.
You know pretty quickly if works or not. Eventually the apps (maybe this has changed) are relatively limited as the cater to the 20 minutes crowd, and you might want to go further.
In terms of depth, Sam Harris has an app where he comingles (IMHO) fairly advanced philosophical concepts. Maybe it's snake oil to you, but feels real and material to me.
That being said, like getting enough sun or eating well or working out...it's optional and there's multiple ways to get there. No need to buy any encyclopedias if you know you're never going to open then :)