Generate all solvable 2xN mazes
Excel, 163 143 bytes
=LET(a,BASE(SEQUENCE(3^A1)-1,3,A1),b,FILTER(a,ISERROR(FIND(12,a))*ISERROR(FIND(21,a))),SUBSTITUTE(b,2,0)&amp;&quot;
&quot;&amp;SUBSTITUTE(SUBSTITUTE(b,1,0),2,1))

Use 1 for walls and 0 for empty cells.
Original
=LET(a,BASE(SEQUENCE(3^A1)-1,3,A1),b,FILTER(a,ISERROR(FIND(12,a))*ISERROR(FIND(21,a))),SUBSTITUTE(SUBSTITUTE(b,1,&quot;X&quot;),2,0)&amp;&quot;
&quot;&amp;SUBSTITUTE(SUBSTITUTE(b,2,&quot;X&quot;),1,0))

Uses 0 for empty cells and X for walls.
Link to Spreadsheet