My phone's disk is getting low on space. The largest apps are Boinc and Google Maps, but both refuse (presumably they aren't compatible with doing so) to be moved onto the SD card. I know Boinc probably has some large files from projects I'm not running at the moment, so I tried to get into the data directory to delete them. But where is it? Looking at the Boinc log via Boinctasks, I see it claims to store data in the folder "/data/user/0/edu.berkeley.boinc/client". Android 11 is being difficult and this path looks different everywhere I look, and I cannot get to the files in it. I tried:

1) USB cable to Windows 11 PC. I thought this showed the whole disk without restrictions. But I see (with the phone set to "USB for file transfer"):
Card, Phone (those are the two drives, card is the SD card, not applicable here). I remember naming these myself some time ago.
In "phone" I have no data folder, but I can go into "Android", which then contains "data". Inside "data", there is no "user", but I do find "edu.berkeley.boinc". This however only contains "files" which is empty. So to summarise I looked for "/data/user/0/edu.berkeley.boinc/client" and found only "Android/data/edu.berkeley.boinc/files".

2) The app "Total Commander" which I read elsewhere shows all files without having to root the phone. On this, I see two "drives" listed at the top with a symbol which looks like an SD card. One is called DICAM-400, which I know to be the SD card, that label was made by the camera I took it from. The other is however called "Internal shared storage". So I think it's not getting to see everything. There's also further down the list a folder icon called "file system root" which I thought would be the real root of the drive. I find: "Internal shared storage/Android/data" but find nothing in there except file commander. I also find "file system root/data/data" but nothing in there except file commander.

Can someone please untangle this mess and stop me going insane? I just want to see what's on the disk and delete some unnecessary things as it's very full.

Unless you ROOT your Android phone (not advised, will break warranty, etc) there's nothing you can do to get to the "locked or hidden" files and folders.

Even if you root phone, you still might not have complete access to all files and folders.

You can do a project reset on the ones using the most space. This will free up space until it reloads files needed to run the specific project.

The directory is ./data/data/edu.berkeley.boinc
That's root/data/data/edu.berkeley.boinc with the second data directory structure hidden (and thus the BOINC directory as well).

But as said, even with the phone rooted, you will not be able to access it. Android's too well secured for that. Follow Dave's advice on resetting projects.

I've managed to access these files before, but I may be remembering an older phone which I did root. I don't mind rooting a Boinc only device, but this is my main phone, and I don't want to make a mess and lose anything I'd have to tediously set back up. I also found rooting causes viruses. I never found a respectable rooting program. Apparently Kingo Root was a very bad choice.

I shall reset all projects not currently running.