>>4463688Sensor size varies on astro cams, it depends on what you're imaging. Actual deep sky tends to prefer large sensors and correspondingly large pixels to gather more light for dim targets such as galaxies and especially nebulae, while cameras intended for planetary imaging have smaller sensors to get a smaller field of view (roughly, but not exactly equivalent to magnification). Planets are small but bright so no worries about wasting light.
Most of what I know about AP, I know by proxy. I'm ironically a visual astronomer. Since you're approaching from the photography side, I think it would be best to just get a camera that suits your needs off the telescope first. Handheld cameras are already not an optimal tool for AP, it's just one that some astronomers already had and realised they could use and get good enough results. If you end up really getting into AP you will want to get a specialised astro cam anyways.
That being said, I'd generally err towards a larger sensor size. You can't move your feet to get closer or farther in AP so the only way to get a (appreciably, focal reducers don't do that much) wider field is to use a shorter telescope. But there are many creative ways to get a narrower field, such as Barlow lenses, eyepiece projection, and afocal projection.
I took picrel with a phone camera btw
