From a UX perspective,
can we do better? I'll base both off my personal experience - Kmail and KDE Telepathy - since those are my email and IM client.
In kmail, to use GPG keys, I need to go to Settings -> Configure -> Identity -> Modify -> Cryptography, change my signing and encryption keys (and it supports PGP or MIME) and then, since I don't already have keys, need to open Kleopatra, the KDE GPG client.
Kleopatra uses keys.gpupg.net as its default keyserver, and you can do file -> new certificate to make one. Its a wizard, so you go step by step, setting up a password for the cert along the way. You also make a revoke cert you save somewhere.
Once you made the key, you need to export it to the server. And you probably want to make a signing and encryption key, since if you got this far you are already a super techy nerd and that is what makes my point right there.
If you want normal people to be able to use gpg in kmail, there needs to be a wizard just like the "add account wizard" called "Setup GPG" that searches for keys that match your email address first in case you already have them and if there are none generates you new ones and just asks you for the password. It handles the propagation and importing of keys itself because thats not something a user should be dealing with unless they need to.
And even that is unlikely to happen - you want the GPG setup to really be a part of the first-start of Kmail process. Like the first time you open the program and get the "add account" button you should also get "setup security".
But even if you can get people making keys, the UX sucks because it makes them enter a password every time you send an email. You should be able to do what kwallet recently did, and bind the unlock key to your GPG keys to your user session so that when you enter the desktop via SDDM it unlocks your GPG keys just like it unlocks your wallet. Then people can use secure email whenever they want without any bullshit.
There are even more UX nightmares - getting your keys across different computers, easily revoking them if they get compromised, even knowing what that means.
By comparison OTR in Telepathy is almost usable. In KTP you just hit the "use OTR" button and if your chat partner does the same it automagically generates and shares the keys, no user interaction required. The only downside is that you don't get local logging of your OTR conversations - that should definitely be an option, maybe even encrypt them with your kwallet keys! Eh, eh?
But these kind of UX nightmares keep secure communications from being a thing. Mumble is literally the best security solution I have, because I can get a letsencrypt cert, run my own server, put on a password, and anyone chatting on it has perfect security in voice and text - the whole thing is encrypted, I can do my own trust network based off my x509 cert, and it even supports pinned users so nobody can impersonate anyone else.
But I say that its the best because for anyone I invite, they literally just need to enter the password I give them to my server. Sure, its problematic to give them the password if you don't have a secure communication link beforehand, but I guess thats what OTR is for! Oh drat...