EXCEL Online - Pull entire column of data where condition (without VBA)

Question

trying to figure out how to summarise some data quickly.

I have here an example of what I am trying to do in the attached picture.

Basically - I have a yearly planner with some names, and on various dates there's a X marking that person on that date.

I need to be able to summarise on either the bottom or a new sheet, the total days as a list of days where there's a mark. The data also needs to be presented in the same format - with all names shown even if there's a blank in that days cell.

I can't use VBA because I'm forced to use EXCEL online unfortunately.

I basically want (from a coders perspective) select column where column not null.

Can anyone help me understand how I would do this please? If not I'll have to manually go through and pull out the columns on a weekly basis

Thanks!

Example