You forgot https://mapcomplete.org in your list!
I'm gonna be giving a bit of contrarian advise here: don't force yourself. No-one asked you to do this all, so take it easy and one bit at a time. If you are a volunteer, just have some fun with it. When you don't feel like continuing anymore, don't.
Another piece of advice: "if you want to go fast, go alone; if you want to go far, go together". (But the latter is more work). If you live in a medium-sized (or bigger) city, maybe there are a few people interested in joining? Post to the local facebook group and do a small gathering with a cup of tea and map together.
I used this one or a similar one a while back. Pure magic. It started downloading a ton of stuff, and half an hour later I was greated by a (slow) macOS, good enough to do some tests of my webapp on Safari.
One can perfectly use matrix for chat as well, especually with e.g. Fluffychat as client.
And yes, matrix is encrypted too
No, I copy-pasted the same link twice accidentally. Edited and corrected now.
For toilets and showers: https://mapcomplete.org/toilets For drinking water: https://mapcomplete.org/drinking_water (edit: I erroneously pasted the toilet-link here before as well)
What would you use it for?
Verifying the environment - e.g. are the roads not overlapping, still somewhat up to date, ...
With mapcomplete, it is literally clicking 'upload image', taking a picture and waiting for it to be uploaded?
In Belguim, we are importing the official building dataset into OSM, but it is a slow process.
The link is https://sophox.org/