Horrible keyboard on the Librem 5

Is it possible to type diacritical characters on the Librem5?
(It would be weird if not. So, I guess it is.)

I have installed both the Dutch keyboard with “Sun dead keys” (whatever that may mean) and the English Int. keyboard with “AlGr dead keys” (because this sounds a bit like the good old US International keyboard with dead keys that worked so well on ‘traditional’ computers).
Neither gives the hoped for results.

So, your advice would be most welcome.