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?
I've been a Nexus/Pixel fan since the beginning but performance/battery is much better now the Samsungs have the Snapdragon 8 Gen 2 in them.
Camera is decent (marginally worse than Pixel for stills but better for video) and OneUI is far much more customisable and less obtuse than it was in the past.
Asus Zenfone 10 is obviously the best choice physically speaking, since it's I think the smallest high-end phone you can find. But in terms of updates, in my experience with a previous Asus phone (Zenfone Max Pro M2, bought it in 2020, was awesome back then but right now it's just crap with non-stop random reboots, so I'm merely using it for 2FA now), it's not so great. Maybe they changed since then, but even now they offer you only two major Android updates until 2025, and security updates until 2027.
Software updates are underrated and are the main deciding factor on when your phone is going to be obsoleted. I'd look for a Pixel (the 7a is a good fit for what you're asking) or a Samsung instead, as both are quite generous with Android updates. I lean heavily towards Pixel phones because they have better support for custom ROMs (and also because I own a 7a).
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.
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.
It's hard for me as a value conscious person to recommend the 7a over the 6a even though I prefer the 7 a because of the wireless charging. But there's ways to get the pixel 6a for $90 ( We'll technically 50 but you have to buy a $40 plan). From metro pcs although you'll have to wait 6 months to unlock it . But you only need to pay for the $40 plan onc.
But even if you don't want to deal with that hassle it's easy to find it for under $200 on the reso market. Be by the holiday the pixel 7a will start to see sales for $350 or below. $250 on resale.
It's not that I even need wireless charging but I like to have it as a fail-safe in case the port breaks . It's one of the most common things to break on a phone.
I've read grapheneos' supported devices page, it explicitly says that the updates after the phone stops getting support are to reduce the harm of no longer having a phone with security updates, not actual updates
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.