I use a pixel 4A 5G right now, and it’s the perfect size for me, I was planning on upgrading to the nothing phone 2, but it’s very big for my hands, any phones similar to the 4a 5G?
Also look into the Xiaomi flagships. Xiaomi 13 can be had for around £700 if you’re willing to shop around, while the last gen Xiaomi 12 is listed for under £400 on the official Mi UK store. Here’s the size comparison to your Pixel if you’re curious.
A Fairphone 3/4 might be your solution, definitely check it out
They said they wanted to support it for more than 5 years but the industry won’t allow it since they stop distributing the components after a few years, but they are gonna support it as far as they can AFAIK.
FP4 is pretty fucking far from small.
I’m going to throw a curveball and say Xperia 10, or the previous gen Xperia 5 if you can find it for under 700. If you don’t mind the height, the width is quite nice to hold. Software is almost stock android, and the height makes split screen multitasking even easier. Obvious downside is Android updates, which is slower and less version upgrades than Google/Samsung phones.