If you want an alternative to the iOS / Android duopoly, and will accept AOSP (Android Open Source Project) or de-Googled Android, there are AOSP devices (including KaiOS), GrapheneOS, LineageOS, /e/OS, LightOS (Light Phone), and a number of feature phone / dumbphone OSes including System30+ (S30+), OpenHarmony, and a few others, see Wikipedia's list: <https://en.wikipedia.org/wiki/Mobile_operating_system>.
Practically, I'd suggest a feature-phone plus either a small laptop (far more capable than iOS/Android), or a tablet/phone running GrapheneOS or LineageOS, possibly one of the full-featured Linux OSes above. Google Pixel is ironically amongst the most viable non-Android hardware devices, with Fairphone and Purism being my next-strongest options. Apparently Lineage is now supporting Samsung's Galaxy series: <https://news.ycombinator.com/item?id=49339930>, and GrapheneOS Motorola support has previously been announced, though remains pending: <https://motorolanews.com/motorola-three-new-b2b-solutions-at...>.
I'm not sure which of these include bundled AI, though I suspect that that's going to be coming to more platforms, absent AI backlash which seems to be swelling presently.