Joy-Cons still in beta
Joy-Cons are still sitting in the Steam Client beta. I've personally noticed random periods of latency, whether or not the controllers are paired together. It's hard to pinpoint when and why it happens, but I notice that it can happen when using the gyro. I've seen this issue pop up in other open source programs that try to tap into the controller as more than an Xbox controller, like reWASD or BetterJoy. Seems that Steam is no different.
Polling
I've read that the polling rate for the Joy-Cons specifically is vaswtly different and concerningly low compared to the Pro Controller and the Dualshock, despite how they all have similar features. It's strange because Joy-Con latency never happens on Switch even at 60fps (frames per second), although dropped inputs are possible in an environment with a lot of spectrum noise.
Best Use of Joy-Cons
I've gotten away with using the Joy-Cons as detached gyro-mice for adventure and narrative games, very comfortable. Sometimes the latency hiccups happen, but with how slow paced those games are, it's easy to remedy or patiently wait for Steam to fix itself. I can't recommend trying anything intense on Steam with Joy-Cons, and it may take some talented minds to reverse-engineer properly how to get these things to work on PC.
Hmm...
Issues happen on a Windows and Steam Deck by the way, across a wide range of Bluetooth adapters. It has to be a misunderstood assumption or three about handling data exchange.
As of December 2022
Joy-Con support is slowly improving. Sometimes, there are latency hiccups whether or not gyro is enabled or controllers are alone or paired, but on the latest stable version it may auto-correct itself over time, but before it felt like the contr0oller inputs were getting either detoured or lost into the void. Finally, the extra buttons on the side are supported, but in classic Valve fashion, configuring them is a clunky mess between handling inputs in the obsolete yet still existing Big Picture configurator, then migrating the updated configuration as a template in the Steam OS (Deck) User Interface. I sweat, the guy that made the Joy-Con ambiguous button icons was responsible for making a cohesive Joy-Con UI, but went on a sabbatical or something, hence the clunky menus during configuration.
As of February 2023
Found this in the Deck UI's controller settings for Joy-Cons, I'd assume other gyro controllers can access this, too.
Gyro Auto Calibration
There's been much debate over the importance of Auto Calibration for gyroscopes within Steam's background. Auto Calibration either over-corrects for bias or doesn't do enough. This finally lets us visualize which values exactly are behaving wonky, and you can tune the tolerance of what Steam considers a bias.
Why I believe Steam Input is in perpetual beta
