In Language and time settings, a new format that also displays Timezone.
We can currently choose between
1:00pm
13:00

but I would also like the option to have
13:00 (UTC+0)

or more geneally custom formats if possible. This is relevant to me for converting emails to pdf format.

If my timezone is Europe/London, I expect the appropriate DST adjustments to be made too. (display summer times as BST, winter times as GMT)

I would also like to be able to choose timezone displayed, rather than it automatically be taken from my system.