You are way past the point of overthinking this.
I have ever once cared how.many lamps firmware updates I ‘can do in a night’ they get done when they get done.
If I were still working in system management caring for 65000 workstations that need updates sure. But no the lights get the firmware when I get to them IF I’m solving a particular problem. You don’t redesign your zigbee network for that.
IF I’m solving a particular problem
Exactly! I’ve never understood the fascination with updating firmware. That’s one of the draws to the Zigbee network for me, it’s isolated by design, so unless a firmware update fixes a problem or brings new functionality, that I need, there is zero reason to apply it. You are just risking a change they breaks functionality or evem a bad update bricking your device.
@Sawtaytoes To see what Z2M exposes, you can go to Z2M page and see exposures for specific device. For instance for your apparent device: Inovelli VZM36 control via MQTT | Zigbee2MQTT
And don’t forget that you can use Z2M to communicate with other MQTT devices too.
I don’t think I need to convince you between ZHA and Z2M. I close the discussion at this point.
How much trouble/work is creating a quirk and can I access remaining “values” without it?
For instance, I have a aqara h2 eu dimmer. Zha cant control dimming and a lot of configuration options are missing.
Values like controlling the led. Set minimum/max brightness (which is essential)
Why did you buy it?
Isn’t this Home Assistant 101? Before you buy a gadget, make sure it works… 
Because I was under the impression that it would be possible. Their matter installation can do it, their own zigbee hub can do it and I read that it is compatible with HA . Nothing indicated to me that the brightness setter wasn’t available. I believe that z2m has the functionality though.
And from what I read online I was also lead to believe that it would work.
Don’t understand. Your link is to a two-month-old GitHub page which says it doesn’t work… 
That issue I didnt see before buying. Its about a “quirk” which apperently is requires for zha.
Or can be easily returned.