What do you intend to do with the pump? Inflate the tyre after patching it up yourself or inflate it to get you to the nearest tyre shop? If it's the latter, if the leak is bad enough to flatten the tyre (nails usually cause very slow leaks), a pump won't help much.

Do take note that for regular topping up of tyre pressure, you don't need much volume - I use a bicycle hand pump for that.
To inflate flat tyre, you need a lot of air so make sure to research and ensure whatever cute pump you buy can deliver that much air continuously.

I'd also buy a manual bicycle pump as a backup and for peace of mind. You can use it to let the electric pump cool down.