there are now many films, yes! but they are also more expensive than normal bluerays ...
You can check out the assortment at https://www.wog.ch, for example!

and yes, it also plays normal films and even DVDs and supports upscaling up to 4k (all this is described in the specifications)...

because the player can of course also be used with "normal TVs" (FullHD), then you won't gain anything with a 4k player ...
so if you have a FullHD TV, this purchase is definitely not worth it !