A more mature alternative would is Nextcloud as it offers a lot more, but setup is reportedly more involved. It does appear to be available for enterprise customers as hosted version as well though: https://nextcloud.com/office/
Not exactly free as in free beer but Collabora, and their 'Collabora Online' suite fits your description. It's effectively online hosted libre office with a few extras.
Facebook made a Twitter (now X) clone (Threads) and has reportedly more users than X now [1]. They have also started a Reddit clone as well now (Forum)[2]. Not sure if that one will be a success as well though, as Reddit isn't loosing users like X is.
Reddit was waiting for Digg to have an incident and milked it to billions. Why was there no project waiting for Reddit to have an incident? (It has had many).