Welcome to the pursuit! I also collect with my son, a 3rd grader. Before the pandemic, we would visit local card shops and flip through bulk together, searching for first editions in Base, Jungle and Fossil. Not a bad deal at 10 cents each, even in LP condition, and kind of a fun activity to do together. We’ve completed about half the checklist of each of those sets, with multiples of several cards. He likes it.
My more serious collecting focus is on pre-TCG Japanese sets, some Carddass and TopSun but primarily the 1997 Tomy Scratch Cards. I’m working on completing sets of series1 and series2 (unscratched), which requires a lot of importing from Japan and may take a while. Majomaal did a really great comprehensive summary of this set here: www.elitefourum.com/t/tomy-1997-pockemon-scratch-card/21642/1
Good luck, and most importantly, have fun!