My new neighbour had them fitted in her bungalow before she moved in as part of a huge renovation, she has them in most of the rooms, vented into the roof space then out through air bricks. I was very tempted but my bungalow has a dormer bedroom so my main rooms are all downstairs with no roof access.
My neighbour had been using a portable unit while waiting for her full system to be installed and she has lent it to me to try. It’s brilliant, I use it in my bedroom over night and in my lounge during the day. It’s a bit heavy ( I am 70) but I can push it on the castors the short distance between the two rooms on laminate flooring, luckily I have plug sockets close to each doorway so don’t have far to move it.
It does not have vents, the moisture collects in an internal tank similar to a condensing tumble dryer, which I need to empty every week or so.
I plan to buy one once they are back in stock, might even get two depending on the price! It has certainly helped me sleep better while I’m recovering from knee replacement surgery.