So about that Nextcloud thing. I've moved to an offline sync 
strategy.

I can sync my Bold 9900 to Outlook (and my work MS exchange 
account) via BlackBerry Desktop Manager over bluetooth (my 
work laptop runs Windows 10). But I didn't want to sync 
_everything_ to my work account, and so I was searching 
around for a solution to that problem, when I found a page 
that explains how to create a completely offline Outlook 
account[1].

The nice thing is, once you have a secondary offline account 
set up, BlackBerry Desktop Manager allows you to choose to 
sync some stuff with the online Work account and some stuff 
with the offline account.

So I'm syncing my calendar with my work account. My 
contacts, notes, and tasks sync with the offline account, 
because they're none of my employer's business. When I 
change computers, I can just copy the offline account's .pst 
file over to the new computer and continue on (as long as 
BlackBerry Desktop Manager keeps working on Windows 10). 

Until my carrier kills 3G (probably a few years away), this 
is how I'm going to continue. I've had it with storing my 
non-work personal information online.

Now if I could just make BlackBerry Desktop make that cool 
Palm sync sound when it runs :P

[1] https://www.msoutlook.info/question/using-outlook-without-an-email-account