I switched to work-from-home years ago because of a medical condition. When I'm at home, if I'm not required to be on video conference or have or expect company, it's cozy comfy practical lounge wear all the way!! This is one of the advantages to being a woman at home! And it makes dressing up to go out all that more pleasurable.
Sweat pants and sweat shirts- I now have an array from my kids' colleges, and DH's because we were recently at his reunion.
Victoria's Secret or Gap or Target pajama sets in flannel or modal... I get solid colors like black, which can look passable if I need to toss on a hoody because someone's arrived at the door. VS' XS works just fine length wise for me. For Gap & Target, if there aren't any petite choices, then I select ankle length.
Another great place to shop for cozy loungewear is Aerie. My DD#2 is all about soft and cozy, so she has totally turned me on to Aerie, her favorite source.
Smart Wool leggings + top set (black) are a splurge but totally 100% worth it. Nothing could be warmer and softer and cozier in the winter. I also wear them under gear to exercise outdoors... when I am okay enough to exercise.
Similarly a North66 set, black, purchased on a trip to Iceland.
One thing on my list for ages, which is even more of a splurge, is a cashmere set -- hoodie and sweat pants. OMG. How wonderful would that be???
If you want something more dressy, then I highly recommend you check out Theory's pull on leggings, which have 5 pocket styling, so they look like pants, but are leggings. SO incredibly comfortable. I am 5'0 tall, so they are super long on me and need to be hemmed, but these will be my "go to" slacks for airplane travel.
For tops I have a stable of Jcrew vintage tees - they offer them in petites. So soft. Wear and launder well. Loose/fluid fit, but sized just so for us shorties. I also have a stock of cotton camis I got at H&M. H&M has the best camis. They last forever. With adjustable straps.
If your puttering includes cooking and cleaning then invest in a fabulous apron or two. Something that makes you smile. Yes even if you are wearing "just" loungewear, an apron is a necessity.
Socks, if you don't wear shoes in the house (we don't): look for cashmere blend. Target often has good choices for this. Smart wool socks are another great choice.