Can anyone tell me if there is a way, a registry tweak or something that will let me make changes to the lock screen slide show or software to replace the lock screen slide show?

a) I want to turn off the mosaic/multiple image feature so that every new image is full screen.
b) I'd like to slow down the speed of the slide show so that images stay visible longer.

I used to use spotlight and was happy with this but lately I keep getting images I don't like, mostly paintings and clicking "Not a fan" has not affect.

I've switched to the slide show hoping to more or less replicate spotlight using my own choice of photos but find the mosaic feature crops photos badly and with the images changing so quick it is distracting when sitting close but not using my laptop.