I have a problem (objective: Data Recovery)

To install TWRP (it seems, I need, explicitly unlocked-bootloader) To unlock bootloader I researched and saw some methods:

• Official method (tedious and If I understand it correctly, implies flashing some Developer-ROM, and “shit”) (I want avoid that)
• non-Official methods (a group of queries, I don’t find too much clear methods) (BTW quality-posts on XDA-Developers have seen better days :'(

The thing is, I don’t want to re-flash some ROM (as I want minimize writings for Data Recovery)

How to check if bootloader is effective-locked ?

Question: I need ways to unlock-Bootloader in this Xiaomi Mi5 device with MIUi 8 global stock (methods, more than one or two, and then I will research about it)

(This is not a trivial-question as in this particular-case:

Logic => unlocking-Bootloader <=> install TWRP to backup partitions (do Data Recovery with them, mounted on PC)

I don’t know, I don’t have (the Knowledge) to do some hack, but I think this has to have proper-solution.

The objective is here: How to recover Data from Android .. sdCard / .. Downloads on Xiaomi Mi5 MIUI 8

Therefore both questions are related to each other…

Any help will be very appreciated (final objective is Data Recovery, but I want to try software, before “JTAG dump” etc (and implications of that process)