I do not think that you need a apk actually.
I am not sure, but in my game, i could just clicked "web player" + "Mobile friendly" after i uploaded it to itch. In Unity, it can automatically detect if the browser version is opened with a mobile device, in which case my mobile canvas is visible. You can also just add a "Mobile controls" button. (which i did as well, just to make sure)
Its not perfect (a bug on top of the screen in the UI, also annoying audio latency) but it is playable, if you would like to check it out on your phone: