Maybe it’s because I live at the shore but our communty college offers outboard motor repair, both beginner and advanced.
Local sailing clubs, USCG Aux. and others offer small boating courses which you need to run that above mentioned outboard motor in most states.
On Meet-up you can find local sailing groups where you can get in some boating experience sailing on someone elses boat for free or a rental, here my share of a rental is $47 a day.
Get your DM rating, that will give you some background running a shop and you’ll need it later to guide guest.
Being a DM will also open some doors to jobs on liveaboards where you will get boco hours onboard but not boco dollars.
Get a logbook going, I was told by a Captain that even hours you are a guest on a diveboat count toward the total.