Other units of the Siberian Host.
It seems that a small battalion was attached in the later stages of the war to each Cossack division. Few would have seen much action, as the new divisions were moved to the front in late 1919 before the plastoon battalions were properly formed.
There is a description at kolchakiya.ru of the uniforms designated for Siberian plastoon units. The scheme has host red shoulderboards with all insignia (buttons, officer lace and cipher) in gold. The cipher is a number plus "Сб.П.". This all follows the standard Imperial pattern. However kolchakiya gives plastoons red red edging on the khaki side, which is rather unusual, and seems bogus. It also says that the plastoons had narrower trousers stripes, only 2.5 cm wide rather than 4.5 cm of the cavalry.
Plastoons would as likely as not have worn British uniforms, as the Siberian Host struggled to outfit its men in Russian styles.
The Siberian Host was not overly blessed with artillery. In the formation of the Siberian Corps in August 1919 the artillery was particularly poorly supplied and trained. However, at least one Siberian Cossack Battery made it to Chita in 1920 and lasted into 1921.
If they followed the WWI pattern, Cossack gunners would have worn the standard artillery uniform (see the Don Artillery).
There is a representation at kolchakiya.ru of the shoulderboards. In Imperial practice horse batteries wore this pattern, but piped around the outside in dark blue and tended to wear coloured trousers at all times.
Field versions were the same ciphers on khaki but marked in dark blue.
The Siberian Host had originally been sent in order to conquer Siberia for Russia, but by the 20th Century was no longer much on the active borderline.
A native divizion was set up from Khakas natives of the Altai region in mid-1919 and sent to Omsk. It seems the motivation was that they were promised Cossack privileges (and may well have been fleeing Red partisans as well). The Khakas are Turkic, and are called a range of names by Russians of the period (Altai, Black Kalmyk, Minusinsk Tatar). Most are Orthodox, which aided contacts, though a few retain shamanism.
After the break-up of the main White armies in late 1919 there was an effort to construct an Altai Horde, formed around the few Cossacks in the area, but including Altai tribesmen as well. The apparent uniform was black, with yellow facings. They fought on for a while, crossing into China when pressed.
The Siberian Host had Kirghiz to their south, but I have seen nothing about their contacts during the Civil War.