Astro Bot has sold 1.5 million as of November 3rd, so in a little under 2 months:
https://www.vgchartz.com/article/463015/astro-bot-sales-top-15-million-units/
Echoes by contrast was at 2.58m (shipped + digital) in its first 5 days:
https://www.vgchartz.com/article/462985/switch-ships-14604-million-units-as-of-september-2024/