56 cards where the card types include “dragon” and the mana value < 5 and the color identity ≤ RU

Atsushi, the Blazing Sky (Kamigawa: Neon Dynasty #134)
Vengeful Ancestor (Murders at Karlov Manor Commander #163)
Thunderbreak Regent (Forgotten Realms Commander #147)
Gadrak, the Crown-Scourge (Core Set 2021 #146)
Leyline Tyrant (Zendikar Rising #147)
Chaos Dragon (Commander Legends: Battle for Baldur's Gate #784)
Shivan Devastator (Dominaria United #143)
Swashbuckler Extraordinaire (Commander Legends: Battle for Baldur's Gate #198)
Reckless Barbarian (Commander Legends: Battle for Baldur's Gate #193)
Renari, Merchant of Marvels (Commander Legends: Battle for Baldur's Gate #90)
Patron of the Arts (Commander Legends: Battle for Baldur's Gate #191)
Galazeth Prismari (Strixhaven: School of Mages #189)
Sprite Dragon (Commander Legends: Battle for Baldur's Gate #852)
Phyrexian Dragon Engine (The Brothers' War #163a)
Manaform Hellkite (Innistrad: Crimson Vow #170)
Smoldering Egg // Ashmouth Dragon (Innistrad: Midnight Hunt #159)
Smoldering Egg // Ashmouth Dragon (Innistrad: Midnight Hunt #159)
Nimbleclaw Adept (Commander Legends: Battle for Baldur's Gate #86)
Territorial Hellkite (Commander Legends: Battle for Baldur's Gate #809)
Invasion of Tarkir // Defiant Thundermaw (March of the Machine #149)
Invasion of Tarkir // Defiant Thundermaw (March of the Machine #149)
Livaan, Cultist of Tiamat (Commander Legends: Battle for Baldur's Gate #188)
Avaricious Dragon (Magic Origins #131)
Opportunistic Dragon (Forgotten Realms Commander #134)
Young Red Dragon // Bathe in Gold (Commander Legends: Battle for Baldur's Gate #210)
Verix Bladewing (Dominaria #149)
Dragon Turtle (Adventures in the Forgotten Realms #56)
Stirring Bard (Commander Legends: Battle for Baldur's Gate #195)
Dragon Egg (Commander Legends #173)
Dragonborn Looter (Commander Legends: Battle for Baldur's Gate #65)
Bhaal's Invoker (Commander Legends: Battle for Baldur's Gate #163)
Slumbering Dragon (Magic 2013 #148)
Arcbound Whelp (Modern Horizons 2 #113)
Moonveil Regent (Innistrad: Midnight Hunt #149)
Skyship Stalker (Forgotten Realms Commander #141)
Archwing Dragon (Avacyn Restored #126)
Phantasmal Dragon (Duel Decks: Jace vs. Vraska #14)
Dragon Hatchling (Jumpstart #310)
Pseudodragon Familiar (Commander Legends: Battle for Baldur's Gate #88)
Furnace Whelp (Jumpstart #323)
Dragon Whelp (Dominaria Remastered #116)
Loch Dragon (Throne of Eldraine #211)
Jaded Sell-Sword (Adventures in the Forgotten Realms #152)
Rakdos Pit Dragon (Ravnica Remastered #120)
Sarkhan's Whelp (Core Set 2019 #299)
Stingerback Terror (Outlaws of Thunder Junction #147)
Fledgling Dragon (Judgment #90)
Oculus Whelp (March of the Machine #69)
Lightning Dragon (Vintage Masters #177)
Nalathni Dragon (Magic Online Promos #35956)
Rathi Dragon (Tempest Remastered #150)
A-Dragonborn Looter (Alchemy Horizons: Baldur's Gate #A-117)
A-Pseudodragon Familiar (Alchemy Horizons: Baldur's Gate #A-128)
A-Young Red Dragon // A-Bathe in Gold (Alchemy Horizons: Baldur's Gate #A-197)
Dragonborn Immolator (Alchemy Horizons: Baldur's Gate #51)
Fearsome Whelp (Alchemy: Innistrad #40)
Scion of Shiv (Jumpstart: Historic Horizons #24)
Town-Razer Tyrant (Alchemy: Innistrad #45)

The arc of my blade has carved a path of light to the end of these results.