Modern commercial image sensors are made in process nodes down to 28nm [0], and for visible light have pixels measuring 0.7-1.5 μm. At [0] there a diagram which gives a feel for what technology nodes are available and used for different applications. For example, RF ICs and power management ICs also typically use larger process nodes, and not just for reasons of cost. In fact a larger node, doesn't necessarily even mean older. For example, many technologies allowing better power handling capabilities in integrated circuits have come exclusively to larger nodes.

Regarding node sizes for image sensors, TSMC built a 28nm fab recently for Sony exclusively to make their latest sensors. There was actually a HN post about that a couple years ago [1]. Also, it's important to note that in many applications, the image sensor layer is now actually stacked, with a layer of DRAM (in 45 nm, for example) between, and a ISP (image signal processor) chip on the bottom made in a smaller digital process. You can see an image of that stack up here [2].

[0] https://image-sensors-world.blogspot.com/2020/08/tsmc-report... [1] https://news.ycombinator.com/item?id=24321804 [2] https://fuse.wikichip.org/news/763/iedm-2017-sonys-3-layer-s...