I feel your pain. I also had to give up my 2017 iPhone SE, too bad. The good thing is that I managed to change the battery myself at least 3 or 4 times, effectively extending its lease. I have since then picked up an iPhone 12 mini, which is only slightly larger and I love it.
What’s wrong with the old SE? I still use mine daily. (Indeed I had to replace the battery too.)
It's no longer receiving updates to the latest iOS, and only gets limited security update backports. Sadly, it won't be long before certain crappy-but-necessary-apps like banking and 2FA auth insist on you installing an update that doesn't exist on iOS 15.
Apps increasingly don't bother testing for the 4" screen dimensions, and if you report that a button or something renders off screen, app devs dismiss your device as "legacy".
I finally got fed up jumping through hoops to make Safari bearable.
I ultimately ended up upgrading to an Xperia XZ1 Compact running Lineage 20. It's the last small android phone with a headphone jack andna flagship processor. Runs beautifully and it's actually a bit smaller than the iPhone 12/13 Minis.