Does anybody have any experience with grass boxes?

my cat is 20 and over the last year shes been struggling more and more with using the litterbox. Ive been to the vet, she´s fine it just seems that she is not a fan of it. I have two boxes, refresh the litter daily( if she used it) and have tried everything i can think of( bigger box, more accesssible, different litter, new litter after every use) but it seems she will prefer to pee on a rag or a tshirt laying on the floor.

Ive been thinking of trying one of those grass matt litter things. My main issue is pee, she does mostly use the box for poo, although in the smaller one she will often not lower her butt enough or just simply stand the wrong way around lol.

Has anybody used the grass ones? theyre a bit pricier so ive been looking for some experience

Thank you in advance!