You'll need a micro-hdmi cable, not mini.

The cheapest maybe, but don't I need to watch for specs and DRM features and everything?

HDMI to micro-HDMI is just a straight passive adapter - only the physical shape of the port is different, and feature support isn’t really a thing. In this case it’s obviously done because the HDMI connector is annoyingly bulky if you want two of them, though I’m surprised a stacked connector wasn’t a better option.

Stacking is risky, because the end of cables might be unreasonably large, thus two might not fit on top of each other that close. Also HDMI cables tend to be pretty bulky, they might simply strain the board too much?

Or there were no cheap enough stacked port.

Oh that is good to hear, thanks!

As long as the cable supports your preferred "version" of HDMI, it should be fine, that cable supports 1.4.

So it's not rated for 4k, but it will support all the DRM stuff.

Not that it's terribly relevant, as the board doesn't support the DRM stuff anyway.

Sure I can just buy an adapter, but then I have to keep track of the adapter and always deal with an adapter hacking of the board making it more awkward to handle.

You make it sound like they are being unreasonable, but just like USB-Micro to USB-C and X to headphone jack, it's a huge inconvenience when you can't find/don't have it to hand.

I used to lose the Micro to C adapters all the time, I lost the C to headphone for my OnePlus6T while travelling and was unable to find a replacement so no headphone use for me.

Also, I have about 12 Raspberry Pis, as many display devices, a dozen or so other HDMI devices such as consoles etc, and tens of normal sized HDMI cables lying around and they're all compatible.

So just have the adapters plugged into the Pi all the time. I mean, what else would you use them for? Problem solved, no drama.

You're not wrong, but it feels like an unnecessary problem to have, stacking a couple of full size HDMI ports would have been nice, or just putting a single port on since having two on a Pi is kinda unnecessary.