A small group of sidthimunki, say 6-7, with the same number of harlequin rasboras would work. Not ideal maybe but ok.
There are some small schisturas & nemachelus that might work. More brook stream, less current than true hillstreams. Most are quite territorial with each other & other bottom fish but I have s.savona that aren't. Unfortunately I've lost some in quarantine.
I also have crimson loaches in a 29g (same footprint), they are more crabby but not nearly as bad as nemachelines get. Maybe a single fish of an aggressive but small species, although I prefer to keep groups. Many prefer a slightly cooler temp so some whiteclouds could work with them.