I managed to get quite a usable list by sniffing out the versions within the SProcs' source code, as stored within the `sys.comments` tables.

[![enter image description here][1]][1]

A healthy amount of assumptions was made, so **test this code on a solitary test instance first**, before going wild on your multitude of Production servers...

    IF OBJECT_ID('tempdb..##BlitzVersions') IS NOT NULL
    	DROP TABLE ##BlitzVersions;
    
    CREATE TABLE ##BlitzVersions (
    	 DBName			   NVARCHAR(100) NULL
    	,SProcName		   NVARCHAR (50) NULL
    	,VersionString	   NVARCHAR (50) NULL
    	,VersionDateString NVARCHAR (50) NULL
    	);
    
    EXEC sys.sp_MSforeachdb
    	 @replacechar = N'?'
    	,@command1 = N'USE[?];
    INSERT INTO ##BlitzVersions
    SELECT
    	 DB_NAME() AS DBName
    	,SUBSTRING([text], CHARINDEX(''sp_Blitz'', [text], 1), 18) AS SProcName
    	,SUBSTRING([text], CHARINDEX(''SET @Version'', [text], 1) + 5, 15) AS VersionString
    	,SUBSTRING([text], CHARINDEX(''SET @VersionD'', [text], 1) + 5, 24) AS VersionDateString
    FROM sys.syscomments sc
    WHERE sc.[text] LIKE ''%sp_Blitz%''
      AND sc.[text] LIKE ''%SET @Version%''
    ';
    
    SELECT *
    FROM ##BlitzVersions
    ORDER BY 1
    
    IF OBJECT_ID('tempdb..##BlitzVersions') IS NOT NULL
    	DROP TABLE ##BlitzVersions;


  [1]: https://i.sstatic.net/WLWrk.png