Is this correct? IgnoreMounted = (1 << 1) = 2 == IgnoreUnavailable?

That's a sneaky question! :-)

As you are not iterating over sorted keys, just directly iterate on the map.

Why are you fetching the url a second time here? url == map[key].second.

You filter a second time here (first time in createList).

I would propose to use the same format independent of the Ignore(Un)Available.

This needs improvement - if you only print the inaccessible ones, the count is off.
Better explicitly mention number of Total, Accessible, Inaccessible.

Hm still awkward:

IgnoreNone = 0,
IgnoreAvailable = 1,
IgnoreUnavailable = 2,
IgnoreMounted = IgnoreAvailable << 4,       <--  (1 << 4) == 16
IgnoreUnmounted = IgnoreUnavailable << 4    <--  (2 << 4) == 32

I'm not content with this solution. Still, it's the best I could do without bloating the code too much.

see above

I think this becomes a little bit clearer if you move it to the top of the map iteration and use a continue; to process the next item, e.g.:

quint64 id= it.key();
deviceId = idToDeviceId(id);  // idutils.h

if (!includeIds.isEmpty() && !includeIds.contains(deviceId)) {
    continue;
} else if (excludeIds.contains(info.deviceId)) {
    continue;
} else if (urlFilter && !urlFilter->match(it.value()).hasMatch())
    continue;
}

checkedFiles += 1;
FileInfo info; 
....
if (info.accessible)
   accessibleCount++

if ((info.accessible && !(accessFilter & IgnoreAvailable)) ||
    (!info.accessible && !(accessFilter & IgnoreUnavailable))) {
    result.append(info);
}

ignoredCount = map.size() - checkedFiles
inaccessibleCount = checkedFiles - accessibleCount

for the second, return

struct summary {
    quint64 ignored;
    quint64 accessible;
    quint64 inaccessible;
};

You can omit DatabaseSanitizer:: here

Thats probably not what you want - IgnoreUnmounted (mounted-only) implicitly includes IgnoreUnavailable, so you will exclude listing unavailable files even on mounted filesystems.

double QDebug

added in D11753