Google is bringing Android apps to Chromebooks (Chrome OS) via the Google Play Store. You can download and install Squid through the Play Store on your Chromebook.
Squid was demoed at Google I/O 2017 as an example of an app that runs well on Chrome OS and takes advantage of features like stylus support on devices like the Samsung Chromebook Pro.
The Play Store for Chrome OS is currently still in beta, so you might encounter issues with Android apps. See below for known issues with Squid on Chrome OS. For the best experience, make sure your Chromebook is up-to-date with the latest updates to Chrome OS.
Connecting with other apps
When importing a PDF, adding images, or exporting a note, other apps such as Drive or Gmail do not appear as options. Unlike a phone or tablet, these Android apps are not installed on a Chromebook by default. You need to install these Android apps from the Play Store in order for them to show up as options. This is different than having the Chrome apps installed. Please see this article for more details.
Rotating the device sometimes results in Squid no longer being fullscreen. This issue has been resolved in the latest update to Chrome OS. If you're seeing this issue, make sure you've updated Chrome OS to the latest version.