Can I use pon without location access?

Yes. If you declined location access, pon briefly asks as you check off: „Start shopping at …?“ After your yes the app behaves exactly as if it had recognized the store itself. Ending is just as easy: tap the small shopping icon on the store section and choose „End shopping“ — or „⋯“ at the top right → „End shopping“. That is also where you switch stores if you need to.

Everything essential works this way: grouping by store, pinning the store you are shopping in, pulling in the items that are also available there, the aisle order learned for that store, the automatic learning of alternative stores, the note to your list members („… is shopping now“) and the statistics about your shopping trips.

Still: do set location to „Always“ — then pon recognizes your stores without asking and reminds you in passing, even when someone just put something on the shared list. We never learn your location (iOS merely gives the app a brief nudge when you are nearby), and it costs practically no battery — your iPhone always knows where it is anyway. You can grant access at any time in your device settings under Settings → pon; the prompt then disappears by itself.