I'm not sure I find letting people handle my phone to be intimate, per se, but it definitely feels high-trust to a much higher degree than most things I do in day-to-day life are. This includes most forms of physical and emotional intimacy; I'm pretty happy to engage in relatively high levels of physical intimacy with strangers or near-strangers, the main thing keeping me from being emotionally intimate with people tends to be social anxiety rather than trust-related concerns, but I need to think hard before giving even people I know relatively well free reign to navigate around my phone.

(Letting people interact with my phone within a specific relatively-constrained app while I watch to make sure they don't leave said app, or letting people hold my phone when it's locked, are different matters. Those are basically fine with me, and I occasionally will (for example) ask physically-nearby friends or family members for help with whatever puzzle I'm stuck on in whatever puzzle game I'm playing at a particular moment. But letting people play around with my settings or my files, or install apps, or use my web browser with my logged-in accounts, or anything else along those lines, are very much high-trust things for me.)