I’d say it didn’t fail. It was never really a consumer phone. It was an attempt to get hardware in the hands of developers, and it achieved that.

Other posts here discuss why it didn’t receive wider adoption.

I daily drove my PinePhone until I could no longer receive MMS messages, since my service provider has a different APN for the internet and MMS. That, and the modem became more unreliable over time. I like my PinePhone, but an average user would never adopt it as it is.