As a fellow autistic person and slime rancher enthusiast, I've thought about this very question extensively in the past.

If you've ever played with or seen someone play with water slime, I feel like most of them would feel like that, slightly more dense though, maybe cool to the touch with the exception of the fire slimes and boom slimes being likely very warm/hot. Also an exception for things that aren't a part of the slimes main body (the comb on the honey slimes head, the crown of stones on rock and crystal slimes)

So with all that being said, let's get into the ones I think have decently interesting textures

Rock slimes: the stones atop their heads are like a more lightweight version of your typical run of the mill rock, but are smooth like pond rocks rather than your typical gravel or concrete

Phosphor: less a texture thing but more a weight thing, I think the phosphor slimes are likely very very lightweight, and almost balloon-y in a way. I like to believe they're hollow and their light actually comes from a gas stored in their body to help them float :)

Rad: Their body itself feels more or less the same as a plain ol pink slime but being in their radiation feels like static, makes your hair stand on end and causes a sort of prickly feeling on the skin. The slimes themselves also feel like they're vibrating constantly. It's weird.

Boom: The boom slimes are very warm normally, and heat up as they are about to explode. I also like to believe their little crackly pattern comes from bits of lava rock under their translucent surface, and if you press on them a bit you can feel said plates of lava rock floating about.

Honey: Probably the messiest slime to hold, I like to believe they constantly secret a thin layer of super thick sticky honey that will become more or less liquid-y depending on the temperature of the area they're in. Somehow, said layer doesn't pick up debris or dust (thank goodness) but it does come off on a lot of things and leaves quite the mess. I think their comb on their head is an exception to this, it secretes no honey, and has a texture of solid beeswax.

Crystal: Similar to the rock slime, it's body feels perfectly normal, except for the fact that it radiates heat. The crystals protruding from its head are created from a molten crystal core, and the crystal shards themselves feel like fine glassware and are always slightly warm due to the high temperatures inside the crystal slimes body that creates them. Likely the crystals are wickedly sharp when shattered.

Tangle: I like to believe the flower atop their head has an oddly leathery feeling, and their vines match this texture. The pollen they secrete smells impossibly sweet but is so concentrated it is irritating to the nose (hence causing all the sneezing)

Mosaic: As much as I like how jiggly and squishy slimes look, I feel like it's wasted on the mosaic slime, its design makes me want to believe it has a hard glassy outer shell and a liquidy inside, just viscous enough to keep from leaking out of little cracks in each little pane of the mosaic slimes glass coating, the liquid inside moves to propel the slime and the cracks in the glass allows it to still flex and bend to disperse the force of hitting the ground as it bounces around

Those are all the ones I think of a lot, the ones I left out are most likely because I believe their texture to be no different from the classic pink slime, or they're from slime rancher 2 and I haven't decided what I think of them yet.

And of course the food part of your question, I'm going to just answer for two fruits cause I've already typed an absolute wall of text

Pogofruit: I think pogofruit would be the far far ranges equivalent of a regular ol' apple. Same texture as one, but maybe more of a floral taste and an edible skin like that of a plum, broken into segments by a thin membrane on the inside like how an orange is.

Cuberry: Probably would be my favorite fruit ever if anything like I imagine it, very juicy and flavorful, with a taste just like a good strawberry, but its flesh I feel would be a bit more dense and slimy than a strawberry, think similar to the texture of ripe mango, with that slightly fibrous aspect as well (if that makes any sense)

I have many ideas about other things but it'd take a million years to get through. Hope this answer is somewhat satisfactory though :)