I'm really looking forward to try the updated version of PyBlock, but according to the adjacent threads, there's a bunch of serious issues still remaining. How much of a dealbreaker are they? Is it actually possible to get to the endgame currently?

As far as I know it's functionally complete as in you can finish. It still needs a major balance pass though on somethings

I would say it is not pissible. Because of titanium ore. You can only get titanium ore with the Logistic Sience Pack, but for this you need titanium (Creature chamber for bones, brains etc.)
To get the initial Sap and Moss is also an Issue if you don't have trees and rocks.

Thank you for working on this @kingarthur. I am also looking forward to the balance update on this.

expanding far enough there are some small islands on it you will found trees so i get 1 sap ; i found some rocks and ....(i think unwanted) ressources as 19 mio zinc and other ressources (i can send screens if wanted)
edit
i think @ mapstart i used pyanadon recommended as ressource (i can test this)
same effect if you start an island at mapstart

expanding far enough there are some small islands on it you will found trees so i get 1 sap ; i found some rocks and ....(i think unwanted) ressources as 19 mio zinc and other ressources (i can send screens if wanted)
edit
i think @ mapstart i used pyanadon recommended because all other seem "bugged"