Excel - Extract string between two strings

With Office 365, you can do:

=LET( line, D3,
       sentences, MID( line, FIND( "[", line ), 99999),
       sarr, FILTERXML( "<m><s>" & SUBSTITUTE( sentences, "{", "</s><s>" ) & "</s></m>", "//s" ),
       larr, INDEX( sarr, FILTER( SEQUENCE( ROWS( sarr ) ), ISNUMBER( FIND( "'selected': True", sarr ) ) ) ),
       s, FIND( "'label': '", larr)+10, f, FIND( "',", larr, s ),
       MID( larr, s, f-s )  )

Where D3 is your target cell with your original line.

I suspect there is an easier way with a better FILTERXML hack, but it does not come to me at the moment. If JvdV is on line, he would know. Also, P.b. would probably do this in a better way.

NB: you must be consistent with string definitions. You must use ' as opposed to ".

Another approach is to force the conversions of " to '. This will do that, but it may have unintended consequences:

=LET( line, D3,
       sentences, MID( SUBSTITUTE( line,"""","'"), FIND( "[", line ), 99999),
       sarr, FILTERXML( "<m><s>" & SUBSTITUTE( sentences, "{", "</s><s>" ) & "</s></m>", "//s" ),
       larr, INDEX( sarr, FILTER( SEQUENCE( ROWS( sarr ) ), ISNUMBER( FIND( "'selected': True", sarr ) ) ) ),
       s, FIND( "'label': '", larr)+10, f, FIND( "',", larr, s ),
       MID( larr, s, f-s )  )