I also work from home and feel the need of some kind of "uniform" although I don't currently have one (or not exactly) and I don't face your additional need of clothes that can handle messy work, since apart from household chores my work at home is sedentary and neat. (Uh, unless I spill ink on myself or the furniture, which admittedly happens.)
I share your feelings about leggings and long tunics -- for me, they feel too "loungewear like." The silhouette doesn't flatter my proportions either unless the tunic is essentially a dress, so that is probably influencing my feelings as well.
In any case, the "not leggings" stance of mine is not a problem in summer, when I tend to reach for woven fabrics anyway -- or for linen tees. My work at home warm weather uniform is woven shorts and a linen tee or woven sleeveless top. It's not terribly exciting but it works. When I go out, I usually switch out shorts for a tube skirt, or put on a dress instead, and add jewellery, footwear, and topper (if it's not too hot).
In winter I face a dilemma. Leggings feel too "loungeish," yoga pants feel like gear and remind me of the days when I didn't wear anything else because I had nothing else. My fallback, of course, is denim. I am lucky that I am a relatively easy fit in denim (that was not always the case) and can find jeans that are truly comfortable. But -- I'm bored with it, and sometimes in winter denim doesn't feel cozy enough!!
Sigh.
I've tried ponte pants but I get cat hair all over them. I tried dressy joggers but felt schleppy in them even though they were dressy. I have a skirted legging (butt vest) to try -- but I am doubtful about it. I think for me, denim is it, with a variety of cozy knits on top. I'll probably try the Kut Diana cords this winter as well. I can vouch for the denim version of that jean -- it's one of my first YLF purchases (in white) and I still wear them!
For your situation -- this sounds maybe crazy -- but what about a smock type garment (Etsy???) (or several) -- you know, like an old fashioned artist's smock?? You could put that on over a column of colour (even leggings, maybe) and a thermal undershirt if it were chilly. Throw in the wash afterwards?
Another option: denim or maybe tencel overalls. Sounds a bit 90s, but hey, why not, when it fills a great function. It would certainly say "work."
