To hold on and not give up. To say I'm hanging in there could mean that you're just all right or it could imply something deeper. For example, the person may be going through some rough times, but they're still holding on and living.
Pajama casual is a term used when working from home and preparing for a video conference. All business above the waist and your pajama pants down below.
We have a Zoom meeting in a few minutes and I’ll probably go pajama casual.