Apple clearly doesn't seem interested. The M1 is just a scaled-up version of the iDevice SoCs. From the reverse engineering we've seen so far, it is extremely clear that not even a single step towards any standardization was taken. It's very much the ad-hoc hodgepodge of embedded crap companies build when they only care about their own complete product and don't allocate any budget towards any "refactoring" that doesn't directly benefit the end product.

They use some ancient Samsung UART for debug (because the first iPhones used a Samsung SoC?), old P.A. Semi I2C controller, the Synopsys DesignWare USB 3 controller (just like some random cheap Allwinner/Rockchip/etc), and here's the fucking kicker, a custom Apple interrupt controller and a custom IOMMU too. These probably predate GICv2/3 at least. But there was no reason for them to switch to the standard Arm GIC and SMMU so they didn't >_<