Set your stair to end with a riser.
Adjust the end connection if necessary to allow for the floor slab and bring the slab right up to the riser.
It still may not match the pattern in the treads but at least the top will all be one slab.
I have no suggestion for the wall in plan other than adding a separate fill.
In 3D you can align textures.
Barry.
One of the forum moderators.
Versions 6.5 to 27
Dell XPS- i7-6700 @ 3.4Ghz, 16GB ram, GeForce GTX 960 (2GB), Windows 10
Lenovo Thinkpad - i7-1270P 2.20 GHz, 32GB RAM, Nvidia T550, Windows 11