This depends mainly on coil design. Perhaps the earlier wireless chargers had larger coils (or had big enough holes in the middle) that they could only charge devices with larger receiver coils (phones), as small wireless charging devices weren't a thing yet. The oldest wireless charger I have is a "fast wireless charger" from the Galaxy S7/S8 days, and it charges the buds case, but does not charge the latest Galaxy Watch, for instance. I assume the Galaxy Watch has the smallest coil.
An older charger coil may look like this, to illustrate why it may not work with your buds case, as it would land right inside of this area where there is actually nothing:
Newer designs are smaller and cover more of the "middle" allowing them to still send enough current to charge small devices, looking more like this:
Yeah they sound serious. They've accomplished unification before by mandating every charging port to be standardized USB. It's also why you can charge any phone with any other phone charger, and why chargers have detachable cables. Prior to that every OEM had a different, proprietary charger and charging port, with fixed cables. So that first EU law brought an enormous positive change at the time as everyone had to switch to USB A and Micro USB as the dominant USB ports at the time.
Apple went around it by using proprietary charging port in their iPhones but including adapters with phones sold in Europe so they could still be charged with Micro USB chargers. This enabled them to continue being the black sheep with a proprietary charging port in North America where they didn't have to include those adapters and why you guys still have two or three widespread charger standards, and why you have to ask your Uber driver if he's got "the Android charger" or "the iPhone charger".
This is a new law in this same spirit that also supposedly closes Apple's loophole too, so every common mobile device charges with the same cable type, and that they use standardized quick charging standards. Which is absolutely amazing for the consumer, solves a lot of problems, and reduces e-waste.
I somehow suspect Apple will just say "fuck it" and release a fully wireless iPhone instead though, just to be different.