As long as your electronics accepts European voltage (i.e. 230V), European current will be no problem, provided you don't draw more current than the circuit will allow. Most European receptacles are "fused" to some amperage. In Switzerland it's 10a; in UK it's 13a; in Italy it's 10a or 16a; and in most of the rest (German and French Schuko) it's 16a. Of note, the two round pin, ungrounded "Europlug" adapter is limited by codes to 2.5 amps, so you should not use it with a hair dryer,
Your phone (USB) charges will undoubtedly accept 230V, but check the nameplate. Some CPAP machines do as well, but some might not.