It's in the Face menu, so either select the 'Face' menu dropdown from the viewport header menus, or press Ctrl-F, or press W (context menu) while you have some faces selected.
You can also just right click on the "Poke Faces" menu item, click "Assign Shortcut" and press Alt-P.
- the selection behaviour (A doesn't seem to deselect any more)
Alt-A clears the selection.
- shift-G doesn't work
Shift-G does grouped selections, I think this is the same as in 2.79.
- W doesn't open a menu any more.
The specials menu has gone, replaced by a context-sensitive menu (what a right click might pop up in most apps) So "Poke Faces" is here when faces are selected.
- Shift-tab doesn't change vertex/face/line selection mode any more.
Well, I feel a little embarrassed now - since you're right, my post was inaccurate. The problem with muscle memory is it's hard to put into text. All I was trying to say is, last time I used blender, I felt a bit like I had three less fingers. Obviously, the functionality is all still there. I even think that a lot of the stuff should change - it's just not the case that only a few of the keybindings changed. It seems to me that a lot of the most-used ones have changed.
You can also just right click on the "Poke Faces" menu item, click "Assign Shortcut" and press Alt-P.
Alt-A clears the selection. Shift-G does grouped selections, I think this is the same as in 2.79. The specials menu has gone, replaced by a context-sensitive menu (what a right click might pop up in most apps) So "Poke Faces" is here when faces are selected. Ctrl-1, Ctrl-2, Ctrl-3.