I wasn’t aware of that since I’m also not relying on their binaries. In fact I have already built Qt 6 for i686-w64-mingw32. When I have builds of Syncthing Tray ready it would be interesting to know whether they actually run on the old hardware.
(Note that I compiled and ran Syncthing and Syncthing Tray’s CLI already on s390x which is also not likely to be supported. So not supported luckily doesn’t mean that it doesn’t work.)