How to check Online Status for user?

Hi everyone,

I am a newbie and need your help.

In my glide app, I wish to use a feature where in if someone says “Free for a quick chat” through a form button, then I wish to show it to all the users who also say this within 15 minutes window.

Just trying to understand how do I make this happen to check? Ideas please

Take the current timestamp of the form submission and write it to a Sheet column, then create another column with arrayformula to add 15 minutes to that, let’s call it “available ending” or something like that.

Create an if then else column, if available ending is before now then true, else false. Only show those with true status.