Flathub(based on flatpak) allows easy install & updates to apps on any Linux distribution along with integrating them well with the desktop.
Currently Logseq support Appimage releases, which by deafult doesn’t integrate well with desktop(Issues with launch icon & StartupWMClass in Appimage · Issue #3432 · logseq/logseq · GitHub) & does not perform automatic updates, which is why we have to manually download every new version from Github release page.
Having Logseq available as flatpak will make it possible to easily install or update using a graphical front end or cli on various linux distributions, not to mention the wider reach to users, which could potentially lead to more testing & thus more stable linux releases.
While I understand this might be planned after Logseq is out of beta(& it’ll be yet another stuff to maintain), Flathub also has a beta repository & having it there first could help ease migration to stable branch, when version 1 is released.
On a side note similar applications like Obsidian is already available in Flathub(though not officially supported).
You might want to look at the App Submission page if you decide to publish on Flathub.