@Egika Unless a device follows at least the specification for usb 1.0 (which includes power negotiation for up to 500mA @ 5v) it isn’t allowed to use the USB logo or branding. A chip to handle the spec costs no more than a few pence these days so it’s highly unlikely you’ll buy a charger carrying the usb branding that doesn’t follow the spec.
You could pretty easily test whether a charger does actually do the handshake by sticking a little tape over the 2 middle pins of the USB-A plug or socket as these are the D+ and D- data pins needed for the handshake. If your device doesn’t start charging or takes days to charge you can, I think, conclude it’s only receiving the default 150mA.