Does one exist or is one in the pipeline?

I don’t mean a massive 42t cog but maybe a 34t cog so you have 1 to 1 ratio with a 34/50 compact chainset.

My road/cx bike cassette is 11-27 and sometimes its just not enough. I know I can buy a bigger cassette but I like the smaller increases in gears. I guess it would also be lighter.

I know xtr cassettes are all individual so I could use the first gear from that

Any thoughts or comments? Apart from mtfu?

If you run sram you can get a mtb mech on the back and run a standard 11-36 cassette. Infact that is exactly what I do for my cross/road bike.

If you run shimano (10spd road) I think you can get a 9spd shimano mech and run 10spd mtb cassette, which goes to 34 I think.

If you want a larger range with the same step you need more gears, and the most you can get at the moment is 11.

You can get 32t road cassettes anyway, so pretty close.
*edit* sorry, I should have read it more carefully-you already know about bigger cassettes.

Easiest thing will be to get a cheap road cassette and a cheap MTB cassette, take them apart and make the combo you want. It needs to be the cheap ones as the more expensive ones use clusters of sprockets on spiders, not a stack of loose sprockets.
Will it work? Probably but it might not shift very well on the big jump. You’ll need an MTB mech too for the range.

33t ring and a 11-32 10spd cassette is pretty close…