I’ve used regular trail shoes and running shoes with pinned pedals. Works fine for the road and around town, but IMO does not quite cut it for MTB use. I’ve tried dedicated flat pedal shoes with the sticky soles (not 5-10s, but similar) and they seemed to work a lot better. The sole was stiffer and the grip was like glue. If I were to go with flats for MTB regularly (I am mainly a clipless guy on the trail), this is what I would get.

I will probably get a pair of 5-10s at some point, but due to orthopedic lifts needed, it gets expensive.