Forgive my ignorance (stupidity), but I'm curious as to what type of shoes you're supposed to wear with platform pedals. Did some Googling, but didn't really find a clear answer.

When riding, I prefer wearing running shoes because of their comfort. I would like to get more grip because my foot slips sometimes but I'm not ready to go clipless just yet. Can I continue wearing running shoes if I get something like these: Wellgo B184 Flat Pedals | Platform MTB Pedal | Aluminum

Or is there an alternative that could help my feet stay in the same position a little better?

I'm a big fan of that style pedal, and have them on several bikes. Running shoes stick quite nicely to them.

Whatever is comfortable, has a stiff sole and has good grip.

Yea .. any shoe can be a Cycling shoe with a stiff arch support insole . rubber Sole to grip the Pedal

the Running shoe foam that absorbs foot fall shocks will also soften the pedal force , but just Pootling along, riding on a Nice day, that wont matter.

Classic Vans are great. I ride in Adidas Samba or Adidas Gazelle indoor soccer shoes. Firm with a solid grip. I've added toe straps to my Forte alloy platform pedals and it's just about perfect.

Thanks for the info. Any specific models you guys would recommend?

I question if a stiff shoe really makes much, or any, difference. Even if your foot does flex a bit, the pedals are still going around exactly as fast and hard as you push them.

I sometimes ride with running shoes that are as flexible as slippers. Sometimes with stiff cycling specific shoes. Often at high intensity. I don't think I can tell a difference in speed per effort either way.

Don't overthink it. Just wear what's most comfortable.

At what point does this start to matter? At one end of the spectrum you have folks who are just out for a leisurely ride, and at the other end are the hard-core racers. But in between are the fitness riders... and even in that group there is probably a pretty wide variety. So my question is whether it matters right away while you're new to the sport and still getting in shape. Or do you reach a point (after you've been biking a while) where things like shoes, more than conditioning, are holding you back?

I like the look of the pedal you linked to, but I went with a similar but cheaper option that works well for me:

Robot Check

Basically 1/2 the price, and it grips whatever shoes I happen to be wearing very well. Just be sure to get the 9/16" version.

I'm a fan of buying pedals in person to be sure they are big enough for my feet. Most cheap pedals are fine for me, I've experimented with fancy and they just aren't what I need. I use mini clips which are basically toe clips with the tops cut off and without the straps. these keep my feet in place just fine so I don't need spikes. I use stiff walking shoes but experimented with flexible fisherman style sandals last summer due to a gout attack and was surprised that they were just fine. they have rubber fronts where my running "sneakers" do not and so the mini clips especially the metal ones rub against my toes so I prefer a shoe (or sandal) with toe protection. I'd love to get a pair of MTB shoes.

Pretty much anything that's not open-toed or with a completely smooth sole. I've used similar pedals with everything from sneakers to combat boots.

Classic Vans work great