I only read the first page of replies, so forgive me if I'm repeating something from the second, but why not a cozy cocoon-shaped (or empire waist) sweater dress or tunic with leg warmers or otk socks? You could add an open jacket or cardi to make a column of color. Try the under-the-belly maternity tights mentioned earlier if the other won't stay up on their own.
Finds quit working for me, but here is one general idea, and links to some shorter, more colorful ones at Anthropologie. I know you've never liked leggings-as-pants, but this might be the time to take the plunge Your butt would be covered, but if you need to pull the tunic up in public, no one would be shocked. Then again, these might be long enough on you to be bona fida dresses.
https://www.anthropologie.com/.....#038;type=
https://www.anthropologie.com/.....;color=004 (check out the pic of it with the plaid leggings)
https://www.anthropologie.com/.....8&typ
https://www.anthropologie.com/.....99&am
ETA the find is the worst picture of that dress. I don't know how to change the picture, but it comes in other colors, on the model it does not look like a dark sack that would drape everything, and of course you would have a colorful jacket, a scarf, and some sparkly shoes on with it--the dress would basically be background for your outfit.
One other thought--does the device have to be under your clothing? I have seen people with medical devices worn basically on the waistband of their pants. They look like badasses, unafraid of the medical issue or what anyone thinks, part cyborg and ready to rule over us puny humans. Seriously, if the waistband itself isn't uncomfortable, you could get some kind of holster, like the ones for cell phones and pagers (remember those?) and carry on your usual way.