Even if some strollers could fit ON, backing out is harder. But I think some (or all?) side by sides are too wide.
We rode the Skyliner daily the first week. My son uses a large Convaid chair, it is like a big adult stroller. On Day 1, I just rolled him in, and he just fit (regular line). That was easy enough, but backing him OUT was harder. I managed, but it was not that easy. Fortunately, my son can walk, so went to plan B, and he walked onto Skyliner, I partially collapsed chair (while on the line), and still rolled it on, but it was narrower and much easier.