Minimal sound coming from my MacBook Pro with the volume all the way up...any suggestions

If you have an Intel Mac, then try a PRAM Reset (hold the PRAM reset for at least three chimes or a full minute if possible although recent versions of macOS unfortunately limit it to one activation).

If you have an M1 Mac, then try using this command in the Terminal app to clear the NVRAM settings:

sudo  nvram  -c

You will need to press the "Return" key at the end of the line to execute the command. You will be prompted to enter you admin password, but nothing will appear on the screen as you type the password. Press the "Return" key to submit the password. After this command completes restart your computer to see the volume works any better.

Also check the Sound "Output" tab in the System Preferences to make sure the balance slider is centered so both speakers are being utilized. You can use the slider to make sure both speakers are working.