BuyFromEU

I heard about these from the Netherlands a bunch of times, but do your research on whether they're your best option. Also they offer them for 20€ each and I've seen them for 7 or 8€ I think, (although could be an older generation, these look a bit different to me): https://freshnrebel.com/shop/smart-finders/

Also a company I like called No Longer Lost that sells a different solution, might not be what you're looking for though: https://store.nolongerlost.com/collections/all

Last but not least a personal tip is to have a place near your door where you can actually hang / put your keys. Since I have this little plate in my hallway and 'trained' myself to put my keys there after I unlock my front door I barely ever have to look for them again (it's just my wallet, phone and glasses now lol)