Socket for UK bathroom
I think it is in theory possible for a device like this to be designed and certified as a shaver socket in the UK.  I don't think having output voltage of 5V (or 9, etc) would disqualify it.  I do not however think this particular device has been designed or certified to &quot;shaver socket&quot; standards for use in a bathroom and I don't think such a thing exists.  You should probably install an actual shaver socket, and plug in a regular USB phone charger cube.
I'm generally not a fan of USB chargers wired into the wall because they quickly become incompatible with the charging needs of newer devices, eg QC2, PD, ETC.  A shaver socket and your device charger will give you safety, charging speed and functionality, and future compatibility.
EDIT: Most people can stop reading now.  Adding to my answer that &quot;charging speed&quot; and future compatibility are not unbounded.  A shaver socket may, by the standard, deliver at most 50W but a manufacturer may limit it to as little as 20W within the standard for shaver sockets.  A 20W shaver socket should easily feed a USB charger that comes with a shaver or toothbrush.    It will not however charge most new (in 2021) smartphones at their maximum speed.  A 50W shaver socket will charge any phone or tablet that I am aware of (in 2021) at its maximum speed, along with any other QC2 or QC3 device.  But QC4 and future standards require more than 50W and PD is already capable of 100W output (which will draw more from the AC source)  so don't expect to charge your 15&quot; gaming laptop in the bathroom (as if you needed another reason not to leave your laptop in the bathroom).