Given that the fediverse is very likely to have an enormous influx of users straining the infrastructure, automatically expanding images beyond the thumbnail would compound all the strain on the instances, so I don’t think that I would recommend making that available yet, or at least until some more maturity has been developed into the platform and architecture. I love the idea, and I also find it annoying to have to manually open each of them, but maybe a bit of a slowdown on the doomscrolling is a good thing.