Q: How to Reach Contextual Menus without a Mouse?

Standard ergnomic advice assumes motor abilities I don't have, and could never have. Since using my computer at a desk, with separate mouse, keyboard and monitor, is aggravating my rsi, I'm trying using at in the floor, lying down, and preferably without the mouse.

How can I access contextual/right-click menus without the mouse?

I can't coordinate two hands.

I can reach command and click on the touchpad, but that doesn't open these menus.

I have to disable tapping and gestures to avoid accidentally triggering them.