I am planning to buy a new phone and I would like to follow your guide. The phone brands which you consider as Tier 1 are Asus, Nokia, Motorola, Sony, LG, FairPhone, and Huawei/Honor. In this comment https://lemmy.ml/post/64888/comment/55721 you prefer Fairphone, Xiaomi, Asus, Motorola (if in USA). And for the follow up comment https://lemmy.ml/post/64888/comment/55784 you prefer Fairphone, Xiaomi or Moto. What happened to SONY, and why did you least prefer Asus now. It is not possible for me to get a Fairphone as I am not living in EU. I am happy to go with SONY cause I like photography and their camera department. Also is it possible to get same privacy and security in a SAMSUNG phone if I follow your guide? (Again for the same camera reason),
Bootloader threats are usually state level or the kinds of apparatuses that TSA uses, so if that is a concern, or you know your adversaries are technologically capable, that should be a factor.
For custom ROM, you can use LineageOS or DivestOS, or if you went for a Pixel (which I do not recommend in general), CalyxOS. Or for a non-root device, you can use this program to auto wipe your device if such a kit/tool usage is detected: LockUp (Cellebrite UFED self-defense app) - https://f-droid.org/app/io.nekohasekai.lockup
Non-root is more secure than with root or bootloader unlock. The only feature that my guide cannot provide is running a VPN on top of a firewall in the same user account. Currently only using one tunnel is possible per user account (main and work profiles).
Thank you for your suggestions.