Onlyfun I'd love to own a fully loaded device that is still one hand operatable.
Maybe lobby tech journalists to write articles about how many people want this?
Maybe launch a change.org petition?
Part of the problem is that it isn't enough for a small number of users to really really want a small phone but buy a big one anyway. For Google to build a small phone, probably a fairly large number of users must want one enough that they angrily buy somebody else's small phone instead of a Pixel.
If Google is selling 10 million Pixels per year (source), in three models, that might be 3 million sales per model. If they suspect two million people will rage-quit Pixels to get a small phone (or two million people will shift from Samsung if Google offers a small Pixel), that might do it.
But if year after year 5% of Pixels users really really want a small phone but buy a big one anyway, that might never do it. That said, for a while it seemed as if maybe Apple would ship a small phone every three years, so the situation might not be absolutely hopeless.