As someone who works for Purism on the Librem 5, I have to say that I never had the impression of stagnation due to duplicated effort. Quite the opposite - we benefited a lot from work done on projects like postmarketOS, Mobian or Plasma Mobile, and I'm pretty sure others are benefiting from Purism's work just as well. A lot of stuff is interconnected and the push to mainline as much stuff as possible was certainly worth it long-term, as we can clearly see its fruits in our everyday work now.