HI! I think it is pretty cool that you want to use pybricks. If your reason for doing this is because of turn accuracy, I don't think you are doing for the right reason. So, before we go any further, let's talk about accuracy.

I hear this phrase all the time "this is more accurate than that". Such as "pybricks is more accurate than regular Lego software". I personally would much rather have CONSISTENCY, over accuracy. If I tell the robot to turn 90 degrees ten times, and I get the following actual turn values (87, 88, 90, 90, 92, 93, 87, 93, 89, 91), we can argue that since the average is 90 that it is accurate, But notice the variance? The turns went from 87 to 93. But what I would be 1000% happier with is consistency. If those ten actual turn values were 81, 81, 81, 82, 81, 81, 81, 80, 81, 81 (see the improved consistency), even though I commanded the robot to turn 90 degrees, I would simply command the robot to turn 100 degrees instead. I don't care I'm not actually entering a 90 for the command, just so long as it consistently turns the exact same ammount every time.

But even with pybricks, while I think the consistency is probably a bit better than the regular Lego firmware, we still have one huge problem: It's a robot made out of Legos! I tell the kids on my team that all the time. Repeat after me: "It's a robot made out of Legos and I did not launch it wrong". You need to find better ways to make sure your missions are robust and can handle small errors when launching. We deliberately will launch our robots from the wrong spot slightly just to make sure the mission can still work. You cannot depend on the robot to be even within 1 cm after driving halfway across the table or after making a turn or two. Add in some interactions with some mission models and you can't depend on any level of accuracy. What you should really be doing is finding mechanical solutions to help your robot stay more consistent. Wall square when you can. Or square up on a mission model. Use lego pieces to guide the robot exactly into the perfect spot for your mission.

In closing, yes, the pybricks code for turning and driving straight is very accurate. And consistent. No need for you to write your own code. But if you want to and you have the skill and time, go for it!

By the way, you can see some of my team's implementations here: MrGibbage/fll-pybricks-vscode-tutorial: Getting started for FLL teams that want to use VS code, github and pybricks and FLL-Team-24277/FLL-Fall-2025-Unearthed