The lamps I got had a “flicker-free” mark on their packaging, so you might want to find some with that. (I think this is the one I got, but I kinda doubt you’ll find this greek brand where you live.

Another solution probanly is to go to a hardware store and try each 3000k lamp into the testing plug they have (they tend do have such). Open your phone, turn on the camera, get it close to the lamp and see if you can see any difference in flickering (the store lamps will probably flicker already, so just see if the tested lamp adds any extra flicker).

Another possible solution might be to trst the lamp and try to hear any buzzing sound, but that will probably be very hard in a crowded store.

Apart from all these, lamps have tint. It either goes to green (positibe duv) or to magenta (negative duv) and have a light quality (cri). Get a high CRI lamp, if you want something close to a conventional bulb. Also you need to find something with a neutral tint, which is rather hard. The lamps I got above have a slightly green tint and I didnt like it much, it took me some time to get used to…