Cheaper alternative: flash existing router with DD-WRT or OpenWRT and access advanced features for free.

nothing worthwhile, as it’s not allowed (for a good reason)

carriers who must sell the same phone as an electronics retailer cannot stop you from unlocking the bootloader.

first world countries have carrier locking illegal, and carriers sell the same configuration phones as regular shops.

Your fault for buying a phone that doesn’t respect you: it has efuses (knox). Buying a regular Android phone that lets you fully restore it without a trace is the way to go.

https://myanimelist.net/anime/37141/Hataraku_Saibou