@matigo Last I looked, desktop support for even Mac and Win was pretty rough. Basic stuff like decently functioning window resize was under construction. If you wanted to push Flutter Linux forward, now would probably be a good time. Even the Web is not out of beta as a target platform - phones are where Flutter focused to start.
Fundamentally I don’t expect Flutter apps to fit in on any platform except maybe Android. I see them as promising a consistent branded experience across devices, not a per-device appearance. But one that actually looks pretty good, unlike the hell that is Swing apps. Sun really should have paid some designers back when.
(You can aim at per-device appearance, but it’s definitely more work, and it’s an uphill fight, because you’re doing all your own rendering rather than letting the platform do it for you.)