Nevermind. Answered my own question.
It's now included in the Viewport Control pulldown in the top left pulldown menu in each viewport: [+] Extended Viewports> Grid> Front, Back, Top, etc..
First of all, my apologies if this topic is buried somewhere in the vast message data on this Forum, but...
I recently updated from 3ds Max 2016 to 2021. In 3ds Max 2016 I could set the active view to "Grid" (not "Home Grid", but to a Helper Object Grid). Amazingly, since Hotkeys were switched to a separate customization interface, this option/command doesn't seem to be available anymore.
Can anyone please provide the correct information or workaround?
Thx.