An application I use for a similar “tweeting but for your eyes only” experience is Memos and the MoeMemo’s app.
My main reason for using memos is being able to self-hosted the server and I can use it in the browser and the app.
I second this. Memos was really useful for me before I switched to Joplin, though there was some UI issues with the mobile web interface when I used it (Moe Memoes is new to me, though!). Additionally, Memos is libre software, which Journelly doesn't seem to be.