As I mentioned before, my smooth hound was done on a budget road/gravel/CX type bike. bear in road config, it is 7.2kg and I purposely went for 9speed because cheap Sora short cage + XT cassette 11-34 because lighter than ultegra but after 1 year and 5000k, the 2 smallest cogs are dead.
One of the other big reasons I m keeping it with 9s is the running cost of the derailleurs; despite cleaning and maintaining the bike properly, I go through a derailleur once a year because UK roads are messy/salty etc. a 9s compatible derailleur is £15 to 17... going to Tiagra or 105 or Red rim brake would be nice but maintenance cost would be much higher.

on 20" wheels, I run Sora 9s short cage, Altus M310 with good result up to 11-40 sunrace cassette. Currently, I run the following:
smooth hound road -> 9s sora shifters with sora short cage derailleur and XT 11-34 cassette + 56T Miche crono chainriring
smooth hound CX -> 9s sora shifters with sora short cage derailleur and ultegra 11-25 cassette + 42T Force chainriring
PlanetX giovanissimi -> 9s microshift shifters with sora short cage derailleur and XT 11-34 cassette + 42T chainriring
Frog 52 -> 9s acera shifters with M310 derailleur and sunrace 11-40 cassette + 32T chainriring

Note that I used to run the Smooth hound as a gravel with sora shifter, sora short cage derailleur, sunrace 11-40 cassette and 42T chainring (for 20% offroad climbs)

And because I could
Dahon helios -> 10 ZEE shifter with Zee derailleur and 11-34 tiaga cassette.