ACROSS
 6. <Scandinavians> NORWEGIANS = (IN SNOW GEAR)*
 9. UNI + X = UNIX <operating system>
10. H_ (RAN RAID)* = HARRIDAN <battle-axe>
11. A A out of CLEAR GAY = CLERGY <fathers?>
12. <tech firm> XIAOMI = XI outside ←MO AI←
14. <theatrical> OPERATIC = (ACTOR I)* outside PE
16. <dummy-user> VENTRILOQUIST = (ISN'T OVER QUILT)*
18. YOU ←REBUT← = YOUTUBER <content creator>
20. CH after REIN* = ENRICH <to make money>
21. LAPD ←GO← = LAPDOG <lackey>
23. <larger> KING-SIZE = SKIING* ←EZ←
25. <round> SLUG <clock>
26. <diabolically> FIENDISHLY = H inside (INFIDELS)* + Y

DOWN
 1. <dress> TOGA = (.n)TO GA(g.)
 2. (AIRBORNE KITE)* outside OWL = RAINBOW LORIKEET <parrot>
 3. <mind> PSYCHE = PS ←E_H C_Y←
 4. M + UTE = MUTE <lower volume>
 5. <flag-waving> JINGOISTIC = (GI JOINS)* TIC
 7. <ceremonial headgear> WAR BONNET = W BOATER* outside NN
 8. GLORIED* = GODLIER <more devout>
13. <sacred> INVIOLABLE = IN VIOLA BLE[-w]
15. <one familiar with buzz> APIARISTS = ←ST SIR + A IPA←
17. <promoted> QUEENED = QUE + _E_N _E_D
19. BOGOF + F = BOG OFF <git>
22. <home> DIGS = DIGITS - IT
24. "ZOO LOO" = ZULU <letter in code>