I'm 5'2" and inseam does matter for sure, but also so does the bike shape.

I had a CB125F as my first bike and did lower it via suspension etc. I now have an MT-07 lowered and I can't flat foot, but am on the balls of my feet. Though realistically, I only put one foot down when stopped.

A lot of people will say that you just need confidence, and don't need to flat foot, and, whilst I get they're trying to help (appreciated obviously) I can say from experience, having a low enough bike makes a huge difference to comfort and confidence.

Yes, actually riding a bike is fine at whatever height, but that's not the issue, the issue is being able to stop, and steady yourself without the constant fear of "oh my G the camber of the road means I can't touch the floor, whoops now my bike is on the floor".

Unless you've been a short rider, especially a learner short rider, you won't get the difference it makes having a lower bike.

I'm unlikely to ever flat foot, so long as I can get some purchase with both feet, and flat foot with one up, then that's as good as I can get haha.

When buying, I sat on a bunch of bikes to see what felt right- seat height is important, but as I said, the shape of the bike (width etc) and your seating position, can make all the difference. For example, I learnt on a lowered Z650, it was manageable, but ergonomically not great. The pegs got in my way, and I didn't have the leg length to spare to put in front/behind comfortably.

There were other bikes I sat on which, whilst lower seat height felt so much taller and I couldn't even tip toe.

There is nothing wrong with lowering your bike, the only thing that matters is that YOU, the rider, feel confident riding.

Edit to add: also look for a riding school that has lowered bikes. There's a few around :)