Not exactly the same thing, but SSiW have a postcard club
https://forum.saysomethingin.com/t/clwb-cardiau-post-cymraeg-post-something-in-welsh/21501
There are also a couple of text practice group that I know about. One is on facebook: I think via the Dwi’n dysgu Cymreag group and the other one is on the Telegram Platform. Or you can post stuff everyday on this forum in the Welsh language topic (I can’t find it just now).
Alternatively, even better is the Welsh Speaking Practice arranged by SSiW open to all: Actual conversations by audio or video, one to one or in groups. All friendly and mixture of abilities.