How to open context menu in (MacOS) Finder with keyboard

"Short answer: no.

Most items in the Finder’s context menu are already accessible via the menu bar & any thing in the menu bar is fair game for a custom keyboard shortcut in System Preferences (System Preferences > Keyboard > Keyboard Shortcuts > Application Shortcuts). You can assign keyboard shortcuts for most apps (Firefox excluded) in that panel and that includes the Finder. If it doesn’t immediately take effect, just relaunch the Finder."

"Not quite exactly the context menu, very close however. If you use the commands for Universal Access you can get to the menu for the Task button in the buttonbar.

Press control-F5 to put the focus on the buttonbar. Press tab until the Task button is highlighted, press space to open it, use the arrows to make your selection.

Note that you may have to enable Universal Access, and that you can change the control-F5 shortcut in the Keyboard prefpane. Also, the name of the button may be slightly different in English (I'm running in Dutch, and can't be bothered to switch languages to check the exact translation)."

Cmd + Shift + / will invoke the help menu at the Menu bar. If you're aware of the item name in context menu, you can type it there and hit enter when appropriate entry is highlighted.
Cmd + Shift + / will invoke the help menu at the Menu bar. If you're aware of the item name in context menu, you can type it there and hit enter when appropriate entry is highlighted.

"I do not know of a way to open the context menu for the current selection (which is what I think you really want) but you can “right click” whatever whatever is under the mouse pointer with only the keyboard.

Turning Sticky Keys and Mouse Keys on or off

Shortcuts for Mouse Keys

Activate Mouse Keys.

In System Preferences, search for “mouse keys” and turn it on.

You can also choose to have five presses of Option toggle Mouse Keys.

Position the mouse cursor.
Hold Control.
Press and release the keypad's 5 key (or Fn+I (not L, the one between U and O)).
Release Control.

But, this relies on having the mouse pointer properly positioned. If you have selected the files in Finder without using the mouse then the mouse pointer will likely be somewhere completely unrelated to your Finder task."