I've got two, both Cyclami from AliExpress.
I bought the smallest size for emergency on the road repairs (A2S). That should do two tyres on a charge. However I don't trust the battery, the charge status light system isn't great and it seems to lose charge sitting in the saddlebag not in use. So don't really use it, I am not confident enough with it as my only emergency repair option.
I then bought the next size up, the smallest they do with a pressure gauge (HW125). And that is night and day a better experience. The main reason I bought it was for travelling with my bike - it effectively replaces a track pump. But it's only a fraction bigger than the other one, so easily fits in a jersey pocket. The battery is rated to do 4 tyres, and it has a proper charge status. I use it not just as an emergency pump but also to top the tyres up before the ride - I set to the desired PSI, pump up, chuck it in the back pocket, knowing it still has enough juice to repair three punctures.
So my experience would be... don't get the tiny size ones, and it is well worth getting one with a gauge.