Button Box Matrix and LED function

I've built a button box based on a Pro Micro with a 6x5 matrix grid - inspired by amstudio's button box

I have four LEDs I'd like to hook up.

1a. Can an LED be hooked up in-series with a (the) row or column that is set as the HIGH output (which I've measured as 4.7v coming out)?
b. So output row 1 --> resistor+LED --> button --> input column A?
c. Column A input would act as a ground in that case?
d. Or would a 2v LED not allow digital logic to work and I'd hit that grey zone (neither high or low)?

2a. Or would programming the controller to make another ouput pin go HIGH to a grounded LED when a specific button's coordinate (or row or column pin in/out) is engaged be more feasible?

2a would be preferable as it provides a more flexible solution such as blinking the LED when a button is pressed but only if you have pins available for the LEDs. Use the value of the pressed button to access an array of LED pin numbers