My homelab has some fan-less boxes like Qotom and some thin client boxes being always on. When I need them running on high loads, I put USB fans on them. But then they and the fans gather dusts much easier than the other boxes with internal fans. Now I use a hand-held vacuum to collect the dusts. (Personally, since the vacuum amps lift largely, I will say it is much much easier than 20 years ago when I was using a hand-held vacuum on the network switch racks.)