For work shoes, for slip resistance, I always recommend that you look for a SLIP and OIL resistant sole, and it is good to look for an ASTM or similar rating.
When it comes to flat feet you need something that provides good stability and that has a slightly firmer sole, cushioning is also important if you are on your feet for long time periods.

https://bestwalkingshoes4men.com/best-work-shoes-for-flat-feet – Look at the Merrell Jungle Moc.

https://bestwalkingshoes4men.com/best-shoes-for-retail-workers – Here you can try the Keen Utility, the Skechers Sure Track and the Moab 2 they are slip-resistant and offer excellent comfort features for flat feet.

I must say I have flat feet and I love most Skechers models for flat feet they are extremely comfortable.