Our current Direct3D 11 offer limited support to Windows 7 due to missing OS features. About DX12, I wouldn't expect any further work to bring new features to an obsolete OS. In fact, the sole reason Dolphin still works with Windows 7 is that the current toolset, libraries and compilers we use still provides support for it. The moment Windows 7 becomes a blocker (e.g. not being able to update a external library or use a new compiler feature because of it), support for it will certainly be dropped altogether, without hesitation...
Avell A70 MOB: Core i7-11800H, GeForce RTX 3060, 32 GB DDR4-3200, Windows 11 (Insider Preview)
ASRock Z97M OC Formula: Pentium G3258, GeForce GT 440, 16 GB DDR3-1600, Windows 10 (22H2)
ASRock Z97M OC Formula: Pentium G3258, GeForce GT 440, 16 GB DDR3-1600, Windows 10 (22H2)