Apologies for posting again today but I have been all up and down the forums and I can’t find just a guide for what I need to do before (my primary concern), during, and after changing SIM card to my new phone. I’m changing from google logins (I know, I need to get to that still) on LG Aristo 5 to hopefully no google at all on an iodeOS-loaded Moto G 2024 from open mobile. A comment on my earlier post and additional digging helped me export contacts and notes (my notes app is also my calendar app), and I know the phone is carrier-compatible. But I am so nervous I’m gonna mess something up bad moving the SIM over! I’m very concerned about losing my data. My current question is: what am I forgetting to back up / what other steps am I not considering? There’s tons of suggestions for replacing specific apps but almost nothing about best practices for changing devices while degoogling. Thhaaaaaanks
I would start with checking the internal storage of the old phone for any files you’ve saved on the drive, ones that you don’t want to lose, like documents, photos, recordings, music, videos, etc. Copy all of that to either a microSD card, a USB drive, or your computer, so that you can add it to the new phone later.
You might also want to download a list of all the apps installed on your old phone, so you can install the same or similar on the new phone later. There are simple apps available for this purpose in the F-Droid “store,” and no doubt in the Google Play store. Here’s an example from F-Droid: AppList | F-Droid - Free and Open Source Android App Repository
You can easily install F-Droid on the old phone in order to get that application: F-Droid - Free and Open Source Android App Repository
If you have SMS and MMS history that you don’t want to lose, go to the SMS/MMS app and export it.
If you’re using any kind of chat app, see if you can export your settings or create a backup, to make setup easy on the new device.
Other apps that might have data you don’t want to lose: Password safe, TOTP app, browser bookmarks, browser sync… check every app that you think might have something you don’t want to lose.
If you plan to change email providers, you’ll eventually want to export all your email history, but presumably you can do that from online later.
Also be aware that you won’t necessarily be able to use every commercial, closed-source application on a degoogled ROM.
As long as your old device is available you literally have nothing to lose, just don’t forget that 
For: Messages (SMS), Call List, Contacts.
I always use: F-Droid: SMS Import Export App.
Install the F-Droid Store on the old device and then this app. Install this app on the new device and import it there.
The app is very reliable and that’s how these three points are done.
For files:
Use your PC, connect your old device to the PC and copy what you need. You can then use the method to copy files back to the new device.
(But I would only ever copy the contents of these “root folders” back, not the entire folder itself, i.e. just copy the contents from the download folder to the new device back to the Download folder, for example..)
It may be more difficult with the Notes app. It depends on what kind of one you use. Many have different formats.
If you use the Google Notes app, you have to log into your Google account (I would have to look for the exact link). and do an export of your data, which also contains the notes, which you can then import into a note app on the new device later, which supports this format.
There aren’t that many of them.
I can’t say anything about the apps because I don’t know which one you use.
When I need apps, I always prefer those that allow an export or backup of the data, even better, if this also works automatically.
For example, with the F-Droid app AEGIS, it is possible to back up its two factor authentications and, if necessary, to import them again on a new device.
That is helpful and reassuring, thank you!
Thank you so much!!
Hey, thank you for purchasing from me! Sorry I am a few days behind on some forum discussions 
By your “notes app being your (Google Calendar) app” are they stored as “tasks”? Various components of “Google Calendar” export (including Tasks) and steps to export them are explained here: Export your data from Google Tasks - Google Calendar Help But as @volker01 notes, then importing them in another notes app may be challenging.
In F-Droid if you search for “Google Tasks” I find Tasks.org that can sync with Google Tasks. If you can get this done on your old phone then you can get them out and when you then migrate Tasks.org to your new phone you do NOT need to add the Google Account (I assume it can work this way).
Later you can go to a different note app if you like (I will assume once they are in Tasks dot org it will be much easier to then export import to other formats too. I prefer my notes in text files / markdown so use Joplin (with a self-hosted sync server for multiple devices) but many will have other suggestions.
Good luck!