Best Apps to use to hold longterm stocks question

Hello,

I have a question regarding which apps to use long term. Someone set me an account with webull. I was wondering if this is a good app to continue buying stocks long term.

Im currently in medical school… loans to my neck but it occurred to me that it would be good to own at least one stock from most if not all markets I use/use me…. ex HCA, apple, t-mobile etc

My final question, is this a good approach?

Thanks in advance!