The problem is that even if you avoid squishing the contents when cutting it, you’ll still squish them when biting it.
Samurai Sword. One cut - through bread, salad, plate and table.
This is how it’s done. Doesn’t sound the least bit goofy. Trying to slice a sandwich with squishy ingredients without doing that sounds goofy.
Man up and eat it whole.
When my kids were little I used to cut their sandwiches in 1/4s to make eating simpler. My daughter is now 22, a nurse, living on her own far away.
She visited us recently. When we went out for dinner, she cut her sandwich in quarters and I had to go to the mens’ room to compose myself.