Suggestions for default apps
I read about the apps shippes with /e/, and I had a few suggestions: Regarding the maps app, there's the OSMAnd app. Regarding the PDF viewer, I would suggest Document viewer, as it supports other document formats.
I would strongly suggest replacing Telegram with Riot.im. Telegram has the problem that the account must be linked to a users real identity (the phone number), which is subject to change if the user decides to switch SIM cards. Also Telegram server isn't free IIRC.