My opinions:

An iPad will not charge well on lower capacity chargers that will be fine with an iPhone, or iPad. Generally you can use the more robust charger for all the devices.

Similarly, for PC's, if you utilize a 12volt charger, you might find that you need to use something more than a "cigarette plug". Most won't be able to deal with a discharged battery like a 110 VAC unit can.

If you have a direct wired PC -- hooked to your house bank with a properly sized wire and circuit breaker, then I think you'd be fine.

Generally, a small inverter has advantages in that it provides some voltage protection through its circuits from "start-up" surges.