Forza Horizon 4 doesn't have "nitrous" in the Fast & Furious sense, but it does have a boost system. Trainers ignore the cooldown, allowing you to boost indefinitely.
“Why trainers for Forza Horizon 4 (including build 1477) are dangerous — account bans, security risks, and why the game’s progression is better experienced legitimately.” forza horizon 4 trainer 1477 free
While there is no single "official" trainer under a specific "1477" version tag, several reputable platforms offer free trainers and mod tools for Forza Horizon 4 Forza Horizon 4 doesn't have "nitrous" in the