TL;DR: you cant upgrade conveyor belts.
As of Update 0.3 you CAN upgrade Coveyor Belts. However, it only is a box select so it might as well not be in the game.

So, as you can see from my steam profile I played over 1700 hours of factorio but what you cant see are my hours in subnautica and satisfactory I accumulated on Epic games. its a lot, I have played automation/sandbox/automation games all my life, I love to spend days on a factory, yet I got all achievements and end game performance problems in Techtonica after only 20 hours of gameplay. Techtonica is not worth it (yet).

If you want the long version you can check out my video review on youtube: https://www.youtube.com/watch?v=h-J_-xAl7AI&t=2s

The Good:
-Music
-Voice acting
-Writing
-aesthetics
-offers fully optional multiplayer

The meh:
-asset quality is hit or miss
-progression is a bit cumbersome
-UI and HUD needs some getting used to.
-slow progression (terrible for me, might be fun to you)

The Bad:
-Bugs
-Performace issues
-Crashes
-lagging music (super annoying)
-massively lacking QoL
-immersion breakers
-input processing/mouse smoothing (cant be turned off)

Now, the devs are actually really nice people and they are super honest, transparent and communicative and I am sure that some, if not all issues, will be resolved in the future (certain changes and updates already have been announced) but its not there yet. I'm happy to change this review once the game improves.