How accurate is the advertised battery life on these doorbells?

Treat headline battery claims skeptically. Blink's 'two-year battery life' in particular is challenged by r/blinkcameras and a r/NoShillReviews thread that note the figure assumes light use and that real-world life can be far shorter, while eufy and Tapo's multi-month claims get more favorable but still variable reports from verified-purchase buyers.