With modern electonic devices with USB charging ports you can ignore voltage. The USB standard specifies 5 volts and every device expects 5 volts and every charger provides 5 volts, or very close to it.
Amps, on the other hand, shouldn't be ignored. If your device calls for 1.5 amps and you provide 1 amp it'll take longer to charge or even fail to charge if it's turrned on. If you provide more than 1.5 amps the device will only draw as much as it needs and no harm is done. So make sure you have enough amperage and you're fine.
With older devices not providing enough amperage could cause damage but devices made in the last few years are well protected against that.
So basically as long as they're USB devices just make sure whatever charger you use provides as much amperage as you need and don't worry about anything else.
I have a number of USB charged devices and one came with a 2.1 amp charger and I use that for nearly everything I own. Or I did till last year when I got a USB charger with 5 ports that plugs into the wall and provides 2.1 amps on 6 ports all at the same time. I think it cost about $25 or $30. I've used it on everything since I got it. I've never had any problems. Here's a link to it:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
Barry