I see, now, that when I enter one of those shortcuts using Gboard's onscreen (virtual) keyboard in Android, that shortcut's full expansion is offered at the center of the top bar in the Gboard keyboard. For example, if I type my initials into the onscreen keyboard, my full name appears in that top bar. Then I can just tap that suggestion to enter it into my document.
Unfortunately, this doesn't work when I enter the shortcut using a Bluetooth (physical) keyboard. The shortcut appears onscreen, but Gboard's top bar does not change accordingly. The explanation is presumably that Gboard is designed to recognize only its own (virtual) keyboard.
My question: can Gboard or some other app be persuaded to expand shortcuts entered via physical keyboard? In Word on the PC desktop, the expansion occurs as soon as the user enters a spacebar, punctuation, or Enter keys following the shortcut.