I personally wouldn't give a whole sandwich, but rather bits and pieces if that makes sense? I gave avocado on toast to my 9 month old the other day and cut it into 3 strips, gave him 1 strip to eat at a time so it wasn't overwhelming xx
I've given my son grilled cheese sandwiches. I cut a full one into 2 triangle halves, and I then cut one of those halves into 4 small triangles, and that's what I give him. He can't deconstruct them because they are stuck together, and he loves eating what I eat, so I show him I'm eating the other half of the sandwich. Sometimes he eats it all, other times he plays, just depends on his mood
I don't have any ideas for you, but if you do a sandwich be prepared for it to be deconstructed anyway 😂