1x's on gravel setups are not there yet. the gearing has far too wide of jumps.
????
They use off-the-shelf cassettes with gearing that has been in use for about a decade now.
I can under understand an 11-speed cassette that goes from 10-42T.... but... regular sized cassettes have been that used for a long time now, even a 11-36T.
If you want less of a jump, then don't go for a huge difference between small cog and climbing cog.
SRAM PG-1130 cassettes for example:
11-26t: 11,12,13,14,15,16,17,19,21,23,26
11-28t: 11,12,13,14,15,16,17,19,22,25,28
11-32t: 11,12,13,14,15,17,19,22,25,28,32
11-36t: 11,12,13,15,17,19,22,25,28,32,36
11-42t: 11,13,15,17,19,22,25,28,32,36,42
Compare to a 10-42T
10,12,14,16,18,21,24,28,32,36,42
About 10 years ago, people started to use 32T cassettes, while being mocked by others, though that was with 10-speed cassette... (I have a Shimano 9-speed XT rear derailleur to use a 10-speed 11-32T cassette with my 107 crank and shifters)
Plus, 1x is already used on cyclocross...as you really don't need to worry about a chain drop like you would a 2x crank. I personally wouldn't mind a 1x on a gravel bike... it's one less thing to worry about, except for those long, steep climbs