A piston can be powered by a powered block diagonally above it but it needs an update in order to "discover" the powered block.
You can make it work without both the redstone torch and dust, push the button and, before the button pops out again, place or break any block next to the piston. Or you can use a redstone block instead of the block with the button.
good old quasi-connectivity has been around for quite as while, and was the building block of many redstone contraptions before observer blocks were added. In fact, Observer blocks were created because bedrock edition does not have quasi-connectivity.