Hello.

I have purchased a Pixel 8 having in mind to switch to GrapheneOS. I have installed the OS without issues, but it is now three days that I am trying to figure out how to transfer the data, especially the apps' data, from my current device (Samsung Galaxy A72, Android 14) to the new device.

I've browsed at large the Internet, including this forum, Reddit and so on. but I haven't found a single guide on how to deal with my issue (which I suppose must be common among all the GOS adopters). What I have tried, using the bits and pieces collected in various message threads;

Helium Backup (Clockworkmod): stopped working since Android 11 or 12, also on my Pixel with GOS does not even trigger the relative app when connected via USB (the PC side says it has done it, the Android side waits forever). Ditched.
Samsung Smart Switch: suggested by many, but of course it works (pretty well, I'd say) the other way around, that is to migrate data TOWARD a Samsung device, not FROM it. Ditched.
Seedvault: I've read about it, but I don't see how I would install/run on my stock Samsung device. Ditched.
Enabling Google Services sync/backup: I don't like this path, indeed I've never enabled it on my current device, as I don't want to have Google messing with my contacts, If I have understood the various FAQ/threads I've read, there's no way the data restore would work on GOS (indeed, Google account sync is always greyed out). Ditched.

So, in short, how the APPS DATA transfer is supposed to take place when adopting GOS? Please note, I remark I am not interested in how to move pictures/movies/music, this is trivial and I know what to do. For contacts and calendars I have too other means for dealing with them. What I would really need is to migrate the current data accumulated for each app installed in my Samsung device. Very few of them (WhatsApp, Tasker, ...) have ways to export and import the data/configuration, but the majority has not, and reinstall the app from the store(s) and start from scratch is not an option.

Thanks in advance, I hope to stick to GOS and to not go back to a proprietary Android.