Changes made via apt will get over-written on the next update. ADB to external devices is not functional. SSH is the way to access the device from a computer. I can't say about recovery mode. Never tried adb there.
adb via ssh, or terminal, errors out because it is looking at the anbox kernel. But, you don't have the rest of anbox installed. If you follow the anbox instructions without installing the kernel, you will get it running - sort of. The base anbox works, but apps appear as a black screen because the patched driver is in kernel 5.8 and hasn't been backported. Otherwise software rendering must be applied. That runs very slow though.
@fla Hi! Lol, ok, I joined. There's a lot I need to learn, but I'll contribute whatever I can. 😄
I still plan to develop an app that connects to the WeChat API because my husband and I need it to communicate with his family in China. If China didn't ban Signal and other messaging apps, we would have a lot more apps to choose from.
As above with ubports-installer_0.8.4-beta_linux_x86_64.AppImage failed (latest version available) and I was unable to get the downloaded file SW_binaries_for_Xperia_AOSP_N_MR1_5.7_r1_v08_loire.zip / *.img accepted, I used ubports-installer_0.7.4-beta_linux_x86_64.AppImage, a previous version I still had on my computer and this worked.
After that I was able to reinstall with ubports-installer_0.8.4-beta_linux_x86_64.AppImage (latest version). This time it was not requested to manually download the image file. Installation worked.
Still there is the issue in ubports installer version 0.8.4 (ubports-installer_0.8.4-beta_linux_x86_64.AppImage) that installation of the image file failed before and why it is now working.
The FP3+ just has newer camera and audio modules, the rest is equal to FP3.
As far as I know, Android 10 is mandatory, to get these modules working.
Therefor I think it is a matter of when Halium 10 gets ready and available.
@gt I did some experimentation how to get my old messages and contacts back. Here is the solution, which works (with a little draw-back):
I used the new re-registered Axolotl profile (all files in .config/textsecure.nanuc and .local/share/textsecure.nanuc) as basis.
Then I replaced the database db.sql file with the old db.sql from my December back-up. (Apparently, Axolotl deletes all old messages from the db.sql after re-registration. On the other hand, attachments remain in the profile).
Then I copied the contacts.yml from the back-up to the config folder of the new profile.
This works fine, I see all my messages and all contacts. The only draw-back is that I can only write a message to a contact AFTER this contact has written a new message to me. Apparently, the other person has to re-initiate the secure connection. I can live with this draw-back, as it is a matter of time that all (relevant) contacts will be working again.