NextCloud allows you to share a folder but for upload only.

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For several years I was using TTRSS, but this year I moved to a Miniflux instance that I host at home. I couple it with an instance of Wallabag for saving articles for later reading. I like the experience of the Miniflux PWA app better than TTRSS.

Speaking from experience from the last five years, it’s been pretty good for me.

Nextcloud has chat capabilities. Perhaps it might be overkill for chat alone but presumably you also want some collaboration with documents.

Budibase.

Hashtags are your friend. It also helps if you have some active posters for the tag. I get good content from following #sciencefiction #coffee and #python.