Obviously with iOS this won't work, but then again, iOS devices aren't cheap enough for this to be a reasonable approach anyway.
Device #1: Buy the cheapest device you can. I give my friends specific recommendations. Invent a new burner gmail account for it. Install whatever you want off the Play Store - obviously, use all the normal caution to avoid any malware. Never put any personal info on it, so never put a SIM card in it, just connect over wifi.
Device #2: Buy a nice Android device. Never sign in. Put the SIM card in this one. Side load apps and update them by extracting the APK from device #1. Export your contacts from Google and load them manually (and save a backup). Access your email using IMAP from a third party app. Backup your photos using a third party app. The point is _not_ to use Google Pay, Google Assistant, and Google Cloud.
• Google Maps works without being signed in
• Google Play Store will update Google Maps (and the default apps on the device) without being signed in, but it does use dark patterns to try to get you to sign in
• Android OS updates will work without being signed in
It is more work, no question. It works for me. Your mileage may vary. Disclaimer that I'm posting in kind of a hurry, so I'll just admit the details here probably don't make sense.