Recommendations on lightweight cross-platform Windowing host

Up to now I've been using QT6 to host OCC. But, it's one hell of a platform (with complex licensing) to just host some basic windowing to get OCC operational - and do nothing more with (I have a basic window and buttons - everything else is OCC or local code).

Does anyone have any recommendations for an alternative cross-platform solution to wrap OCC with?

Microsoft is, well, Microsoft (I can't comment on cross-platform capability, never used it).
GTK might do, but trying to get GTK4 operational with OCC is a recipe in futility (prefer not to baseline on old versions).
GTKmm has sample code, but GTKmm4 is (imo) a convoluted mess with no documentation.

Any suggestions - or am I being over-harsh?

Mat