55 cards where the color identity is RU and the cards can be your commander and the mana value < 5

Adeliz, the Cinder Wind (Dominaria #190)
Aegar, the Freezing Flame (Kaldheim #200)
Alexander Clamilton (Unsanctioned #16)
Balmor, Battlemage Captain (Foundations #237)
Baral and Kari Zev (March of the Machine #218)
Bilbo, Retired Burglar (The Lord of the Rings: Tales of Middle-earth #196)
Bjorna, Nightfall Alchemist (Universes Within #2)
Breeches, the Blastmaker (Outlaws of Thunder Junction #197)
Bria, Riptide Rogue (Bloomburrow #379)
Captain Storm, Cosmium Raider (The Lost Caverns of Ixalan #227)
Captain Vargus Wrath (Commander Legends #273)
Dalakos, Crafter of Wonders (Theros Beyond Death #212)
Denethor, Stone Seer (Tales of Middle-earth Commander #20)
Edgin, Larcenous Lutenist (Secret Lair Drop #1242)
Eruth, Tormented Prophet (Innistrad: Crimson Vow #237)
Farideh, Devil's Chosen (Adventures in the Forgotten Realms #221)
Galazeth Prismari (Strixhaven: School of Mages #189)
Ghyrson Starn, Kelermorph (Warhammer 40,000 Commander #124)
Ian Malcolm, Chaotician (Jurassic World Collection #13)
Idris, Soul of the TARDIS (Doctor Who #135)
Jenny Flint (Doctor Who #136)
Jhoira, Ageless Innovator (Dominaria United #202)
Jhoira of the Ghitu (Time Spiral Remastered #256)
Jhoira, Weatherlight Captain (Double Masters #203)
Johann, Apprentice Sorcerer (Wilds of Eldraine #207)
Jori En, Ruin Diver (Duel Decks: Mind vs. Might #23)
Kaza, Roil Chaser (Outlaws of Thunder Junction Commander #232)
Kraum, Violent Cacophony (Outlaws of Thunder Junction #214)
Lilah, Undefeated Slickshot (Outlaws of Thunder Junction #217)
Ludevic, Necro-Alchemist (Commander 2016 #37)
Malcolm, the Eyes (Outlaws of Thunder Junction #219)
Mary Read and Anne Bonny (Assassin's Creed #61)
Mizzix of the Izmagnus (Commander Masters #348)
Myra the Magnificent (Unfinity #175)
Nin, the Pain Artist (Commander 2017 #183)
Ral, Monsoon Mage // Ral, Leyline Prodigy (Modern Horizons 3 #247)
Ral, Monsoon Mage // Ral, Leyline Prodigy (Modern Horizons 3 #247)
Red Death, Shipwrecker (Fallout #116)
Rielle, the Everwise (Ikoria: Lair of Behemoths #203)
River Song (Doctor Who #152)
Rootha, Mercurial Artist (Strixhaven: School of Mages #227)
Roxi, Publicist to the Stars (Unfinity #177)
Saheeli, the Gifted (Commander 2018 #44)
Saheeli, the Sun's Brilliance (The Lost Caverns of Ixalan #239)
Sarkhan, Soul Aflame (March of the Machine: The Aftermath #46)
Shao Jun (Assassin's Creed #63)
Stella Lee, Wild Card (Outlaws of Thunder Junction Commander #3)
Tawnos, Urza's Apprentice (Commander 2018 #45)
The Fifteenth Doctor (Secret Lair Drop #1584)
The Ninth Doctor (Doctor Who #148)
Tibor and Lumia (Guildpact #135)
Uvilda, Dean of Perfection // Nassari, Dean of Expression (Strixhaven: School of Mages #160)
Uvilda, Dean of Perfection // Nassari, Dean of Expression (Strixhaven: School of Mages #160)
Vadrik, Astral Archmage (Innistrad: Midnight Hunt #248)
Veyran, Voice of Duality (Outlaws of Thunder Junction Commander #248)
Yusri, Fortune's Flame (Modern Horizons 2 #218)
Zaffai, Thunder Conductor (Commander 2021 #4)

This search is finished. Now the real work can begin.