Here are all the known customization threads in case people want to post in them and keep them bumped up for consideration:
A Compilation of Customization threads - By Benhart
https://us.forums.blizzard.com/en/wow/t/indexcompilation-of-amazing-customization-suggestions-threads/1112862
Ankoan and Jinyu Thread - By Rorrand
https://us.forums.blizzard.com/en/wow/t/the-ankoan-and-jinyu-race-discussion-thread/167366
Arakkoa Thread - By Lore
Unoffical Playable Arakkoa Discussion Thread
Big Blood Elf Customization Thread - By Veras
https://us.forums.blizzard.com/en/wow/t/big-blood-elf-customization-thread/1008651
Blood Elf Customization Thread (For The Sin’Dorei) - By Kyuu (Fenelon)
https://us.forums.blizzard.com/en/wow/t/blood-elf-customization-thread-for-the-sindorei/1596381
Broken/Krokul Allied Race Thread - By Mianyaue
https://us.forums.blizzard.com/en/wow/t/unofficial-playable-broken-discussion-thread/1274881
Covenant Races Thread - By Emerril
Playable Covenant Races
Customization Suggestions Megathread - By Drede
Grand List of Customization Suggestions
Dark Iron and Mag’har customization Thread - By Grymes
https://us.forums.blizzard.com/en/wow/t/dark-iron-dwarvesmaghar-orcs-next-on-the-table-for-expanded-customizations/1189486
Dark Ranger Thread - By Balesong
Dark Ranger Customization Options Request Thread
Drakonid Thread - By Keldar
https://us.forums.blizzard.com/en/wow/t/megathread-the-other-half-of-the-dragon-fantasy-drakonids/1289454
Dragonmaw Orcs and Wildhammer Dwarves - By Keldar
https://us.forums.blizzard.com/en/wow/t/megathread-twilight-highlands-allied-races-dragonmaw-orcs-and-wildhammer-dwarves/652888
Eldritch Knight/Void Knight Concept - By Greatbrae
https://us.forums.blizzard.com/en/wow/t/new-class-idea-eldritch-knight-void-melee-class/1244333
Ethereal Thread - By Lore
Unoffical Playable Ethereal Discussion Thread
Forsaken Customization Thread - By Baalsamael
https://us.forums.blizzard.com/en/wow/t/forsakenundead-customization-megathread/1074532
Forsaken and LFD Model Toggle Thread - By Greatbrae
Lightforged Dreanei & Forsaken model toggle thread (or sub race)
Forest Troll AR thread - By Zurogrusel
Forest Troll Race/Customization Megathread
Furbolg Thread - By Fenelon
Unofficial Playable Furbolg Discussion Thread
Goblin customization! - By Hendry
https://us.forums.blizzard.com/en/wow/t/goblin-customization-thread/1059517
Human Customization Thread - By Anansi
https://us.forums.blizzard.com/en/wow/t/human-customization-thread/1133366
Kelfin Thread - By Gnomest
https://us.forums.blizzard.com/en/wow/t/the-kelfin-loveallied-race-discussion-thread-✿/674368
Kul’tiran and Zandalari Customization - By Kyzendra
https://us.forums.blizzard.com/en/wow/t/kul-tirans-and-zandalari-customisation-ideas/1099759
Kul’Tiran Love and Customization Thread - By Morbann (Fenelon)
Kul'tiran Love & Customization Thread
LFD and Draenei customization - By Averyx
https://us.forums.blizzard.com/en/wow/t/lightforged-draenei-customization-feedback-thread-currently-the-new-options-are-lacking-in-fantasy/1106830
Mechagnome Customization - By Coaxial (Fenelon)
Mechagnome Customization Thread
Mok’nathal Allied Race Thread - By Mianyaue
https://us.forums.blizzard.com/en/wow/t/unofficial-playable-moknathal-discussion-thread/1274883
Nathanos Style Forsaken - By Fallyn
"Nathanos"-style Forsaken: Vampirates Customization/AR Megathread
Nightborne Customization Thread - By Ellinia
https://us.forums.blizzard.com/en/wow/t/nightborne-customization-thread/1120763
Ogre Thread - By Bagzak
The Unofficial Stonemaul Ogre Playable Race Discussion Megathread!
Big Orc Customization Thread - By Zurogrusel
Orc Customization Megathread (pls give fel orc)
Rajani Allied Race Thread - By Mianyaue
Unofficial Playable Rajani Mogu Discussion Thread
Saberon Thread - By Lore
Unoffical Playable Saberon Discussion Thread
San’layn Thread - By Fallyn
San’layn/vampyr Elf ALLIED RACE Coagulated Megathread of Ideas{Re-VAMPed}
Saurok Thread - By Bagzak
The Unofficial Saurok Playable Race Discussion Megathread! 🐊
Sethrak Thread - By Nadezhdha
Unoffical Playable Sethrak Discussion Thread
Taunka Thread - By Zitga
Taunka Allied Race Megathread
Tinker Megathread - by Tausnor
A Time for Innovation! - The Unofficial Tinker Class Discussion Megathread
Void Elf Customization Thread (For the Void Aspect) - By Fenelon
Void Elf Customization Thread (Ascension of the Ren'dorei)
Vulpera Customization Thread - By Fokoru
https://us.forums.blizzard.com/en/wow/t/vulpera-customization-thread/1203407
Warlock Stables Customization - By Baalsamael
Warlock Customization: More Grimoires! And other stuff
Worgen Customization Megathread - By Keori
https://us.forums.blizzard.com/en/wow/t/worgen-customization-mega-thread/659560
Worgen Tails Thread - By Caelus
https://us.forums.blizzard.com/en/wow/t/give-worgen-tails/504127