User Gallery Widget

You could use a core_v2_searchResult and build the query to list media entities created by the user

This would expose media entries regardless of where they reside on the community 

For example 

#set ($searchQuery = "%{}")
$searchQuery.Add("Query", "type:file AND user:" + $user.Id)
$searchQuery.Add("PageSize", 10)
$searchQuery.Add("PageIndex", 0)
$searchQuery.Add("IsLoggable", 'False')

#set ($mediaResults = $core_v2_searchResult.List($searchQuery))

You would then need to customise the user profile widget to expose the entry and list 

Thanks for the starter information.  I'm currently playing in the sandbox and I've got results (that's good).

Is there any way to restrict this to media galleries only?  Right now it's pulling every single attached file everywhere.

FYI: All of our media galleries are all inside of one container (group), but I don't see a way to do this with a "recurse" option.

I'm very new to working with Velocity, but something doesn't look right on my end.

#set ($user = $core_v2_user.Current)
#set ($searchQuery = "%{}")

$searchQuery.Add("Query", "type:file AND user:" + $user.Id)
$searchQuery.Add("PageSize", 10)
$searchQuery.Add("PageIndex", 0)
$searchQuery.Add("IsLoggable", 'False')

#set ($mediaResults = $core_v2_searchResult.List($searchQuery))
$mediaResults

I'm getting an error: Encountered "+ " at line 4, column 49. Was expecting one of: "," ... ")" ...

I've also tried to put my own ID in place for the search query manually with different error results.

#set ($user = $core_v2_user.Current)
#set ($searchQuery = "%{}")

##$searchQuery.Add("Query", "type:file AND user:" + $user.Id)
$searchQuery.Add("Query", "type:file AND user:2109")
$searchQuery.Add("PageSize", 10)
$searchQuery.Add("PageIndex", 0)
$searchQuery.Add("IsLoggable", 'False')

#set ($mediaResults = $core_v2_searchResult.List($searchQuery))
$mediaResults

Different error: Exception has been thrown by the target of an invocation.

You could add the group as another value AND group:xxx AND 

Where xxx is the group id/number, you can find this in group options at the bottom via the identifiers link

#set ($user = $core_v2_user.Current)
#set ($searchQuery = "%{}")

$searchQuery.Add("Query", "type:file AND group:371")
$searchQuery.Add("PageSize", 10)
$searchQuery.Add("PageIndex", 0)
$searchQuery.Add("IsLoggable", 'False')

#set ($mediaResults = $core_v2_searchResult.List($searchQuery))
$mediaResults

I quickly tried this locally and saw the expected results 

Tried this, but it doesn't appear to recurse into subgroups.  Is that the intended function?

• Shared Content Space [Group]
  • Product 1 [Group]
    • Type 1 [Gallery]
    • Type 2 [Gallery]
    • Type 3 [Gallery]
  • Product 2 [Group]
    • Type 4 [Gallery]
    • Type 5 [Gallery]
  • Product 3 [Group]
    • Type 6 [Gallery]
    • Type 7 [Gallery]

I can get it to render sometimes, but what I'd ultimately like to do is get it to use the "Shared Content Space" as a root and search for any media gallery items for said user.  If that's not possible, then maybe I'll need to investigate another way.

Ah ok, solr/search doesn't have any context of the full group structure 

So you would have 2 choices 

You could iterate through the groups in velocity and build up the query to include something like (group:1 OR group2 OR group:3) 
or if it is just 2 levels (parent/child as above) you could include the parent group into the query so 

$searchQuery.Add("Query", "type:file AND (group:371 OR parentgroup:371)")

Also to limit files to galleries you could try adding apptype:MediaGallery

Hope this helps, solr and search queries can be a great aid but its always a learning curve at the start