What path clearing, weed and moss killing, type weedkiller?

I have a large patch of gravel that’s pretty weedtastic and a decently large area of stone slabs that are slippery-moss-tastic, so I’m hoping there’s a product that I can, I dunno, dissolve in a watering can and pour on that will sort it all. Any such recommendations?

For slabs patio magic worked for us, read instructions, but I think it’s mix, pour over, brush around, leave. However we chose patio magic as the Mrs like plants and it’s meant to be plant friendLY so I can’t see it doing the weeds. I’d have thought any weed killer would do the gravel, but beware if plants you like near it, run off etc etc. If you do manual pulling on a wet day (use a flat screwdriver to help poke out deep roots ) you can probably make a big improvement.

Roundup for gravel, sprayed on a calm day, pressure washer for slabs.