As someone who knows quite little about Android (currently in the Apple ecosystem, but considering jumping ship): When you use these privacy-focused Android versions without Google Play, is there a consistent way to get apps from the Play store to run on there? (e.g. download the APK from somewhere and sideload it). I'd really like an OS that doesn't spy on me, but there's e.g. some goverment ID apps, transit apps an…
The F-Droid app supports adding more repositories (think like apt/yum/dnf on Linux) easily, so you can source software from anywhere which runs their own repository. One of the most popular "other" repos is Izzy (apt.izzysoft.de/fdroid), and there is an alternate project called "microG" which can allow you to use Google Play store apps (microg.org/fdroid.html). microG is how you will get your Google Play apps onto the device, usually (there are other solutions besides microG out there however).
The CalyxOS install ROM includes F-Droid (app and repos) and offers to install microG for you on your first boot (as well as some other opt-in stuff). Calyx runs their own F-Droid repo which is pre-added to the app so you get updates from them as well (think the built-in apps most smartphones have).