As a team that runs a mobile-traffic source with deep OEM integrations, we’ve audited what on-device ads actually deliver in 2025 versus mainstream social/search. The short version: first-screen inventory is rewriting acquisition math — if you activate it the right way. The economics: cheaper clears, earlier intent On-device auctions live where competition is thin and attention is high — during setup (OOBE), in system folders, and on the lock screen. That structural edge shows up in hard results: a REPLUG ride-hailing test cut CPI 32% vs. Google UAC and lifted installs +174% in Tier-2 EMEA; MobileAction pegs OEM buys 25 – 35% cheaper than Facebook across Tier-1; and typical social CPMs in 2025 still sit 2× higher than OEM. Lock-screen “Vertical Ads” (e.g., the AEGEAN launch with Dentsu in Greece) place your creative literally on the first screen a user sees — there’s no below-the-fold guesswork. The quality: native surfaces, stickier users When an ad appears inside trusted system surfaces, it behaves less like an interruption and more like guidance. In the same REPLUG data, Xiaomi GetApps traffic posted +26% D7 retention vs. Meta. Tenjin cites a Hong Kong publisher that gained +20% installs with strong global retention via GetApps distribution. Cheaper doesn’t mean low-intent; it often means earlier intent. Measurement & risk: privacy-proof signals with lower IVT Social and open exchanges are battling identity loss (ATT on iOS, Sandbox on Android) and persistent IVT. OEM supply is different: requests are server-to-server and device-verified, so fraud is near-zero relative to open web norms; GAID/OAID still enable deterministic attribution today while Sandbox testing ramps. Viewability? Lock-screen and OOBE units are 100% in-view by design. The catch: operations — not outcomes Trade-offs are real. OEM reach is predominantly Android; each vendor (Samsung, Xiaomi, OPPO, Huawei, etc.) runs its own console, placements and specs; creative toolkits skew toward clear value props over heavy interactivity. Meanwhile, mainstream channels still win on single-dashboard reach (iOS+Android), mature creative testing suites, and deep retargeting via first-party graphs. Our guidance for 2H-2025 Treat OEM as an incremental growth rail, not a replacement. Start with a high-volume vendor (e.g., Xiaomi) to validate unit economics, then expand. Over-bid for 48 hours to feed smart-bid (oCPC) with ≥30 daily conversions, then shift to post-install goals (D1 retention, registration, purchase) using post-link optimization. Use lock-screen or OOBE for launch bursts, and keep native/icon units always-on for steady scale. Run quarterly incrementality tests — deterministic IDs make true lift measurable even as Sandbox tightens. Conclusion Open, vendor-verified evidence is convergent: OEM advertising delivers lower CPIs, cleaner traffic, and stronger early retention than traditional UA — at the price of Android-first operations and a few extra playbooks to learn. Teams that blend OEM with social/search, wire measurement early, and design creatives for first-screen moments will lock in a durable cost-and-quality edge as privacy reshapes mobile growth. Everyone else will keep bidding higher, one tap later.