Concrete is shaping up to be the new generic building block in the game.

This addition would probably make even redstoners switch to concrete for wire tracing, since one-way slabs can be colored.

Oh and I also basically need it for a certain park

https://feedback.minecraft.net/hc/en-us/community/posts/360010984931-Concrete-and-Terracotta-having-Slab-Stair-and-Wall-Variants

EXTREMELY DIFFICULT (if not impossible)

it's possible to make a falling sand object that looks like a shifted block, which if you block view from below and sides could look like a halfslab.

This is laggy, might dither, needs extra steps (like a boat) to get a hitbox, and are not true slabs.

With a resource-pack it might be possible to fake the half-slab texture to look good from all sides as well, then the datapack would only need to set up the collissions

https://minecraft.curseforge.com/projects/concreteextends https://minecraft.curseforge.com/projects/vanilla-builders-extension https://minecraft.curseforge.com/projects/concrete-mod