I just tried google stitch, itenerates UI design and frontend code directly from descriptions or images.
I gave it a detailed ui specification for an app i am building, told it the 6 pages to focus on (it said it can only do 6 at a time).
and it spit out a very impressive UI design in one shot.
I didn't work out next steps, like getting it in figma, getting the code etc yet but this is definitely worth checking out for your marketing projects, websites and apps
have you tried it? is there something better that you are using for ai page and app design ?