I don't have any gravel bikes, per se, but I recently bought a 1x CX bike mainly for road with an option in mind to handle the tamer off-road stuff. I also have more conventional 2x bikes. My 1x is 11sp with 40t chainring up front and 11-36t cassette. For solo riding, including decent climbs, I haven't noticed any downside. I don't go nearly as fast downhill, obviously, which doesn't matter to me. Uphill, the 40-36 ratio has been a non-issue, maybe because I've done a huge amount of low cadence climbing this year. It helps that no FD means a lighter bike. With a bigger cassette, maybe the tooth jumps will bother you -- again, it's something that doesn't matter to me when riding solo.
You would think that a 2x bike is more suitable for road riding, especially in a paceline, but one of the ride leaders of a group I rode with in the before times used a 1x bike and during a ride I even remarked how smooth his lead was. He would drop back on steeper terrain, but groups usually separate then anyway.