[ASUS ZenFone 6 (2019) Questions & Answers] ChthonVII:
Please forgive my ignorance here. It's been 4 or 5 years since I last flashed a recovery. AB wasn't a thing back then, but it sounds like it obsoleted everything I used to know. Meanwhile, it seems like everyone around here has long since digested the changes and is carrying on conversations premised on a lot of background information I don't know. In short, I'm confused, and I need help.

What I Want to Do:

Flash the microG fork of LineageOS

Flash Magisk

Flash the Asus camera app

Install the unofficial port of the GCam app

Encrypt and divorce the boot password from the lockscreen as per this post (which I can't link to our XDA rejects my post, so I'm copy-pasting instead: https COLON SLASH SLASH xdaforums.com/showpost.php?p=78699812&postcount=58 )

Question 1

Which recovery should I use? It sounds like there are three and each has problems. Is the following correct?

It sounds like the LineageOS has trouble flashing things other than LineageOS -- or is it just OpenGApps that's a problem? Can it flash the microG fork of LineageOS?

It sounds like mauronofrio's unofficial TWRP works generally, but can't flash LineageOS and can't decrypt the data partition if LineageOS encrypted it.

It sounds like bigbiff's official TWRP works generally, but there seem to be differing opinions about whether it can flash LineageOS; it can decrypt a data partition encrypted by LineageOS, but not if a password is set; and its permanent installation feature is currently buggy and might break the boot partition.

Question 2

Some posts suggest using different recoveries to flash different things. Is that advisable?

Question 3

Do I even need to install a recovery permanently? It sounds like it should be possible to boot a recovery using "fastboot boot something.img" and do everything I need to do. Is that right?

Are there any strong reasons why I should have a recovery installed permanently even if it's not necessary?

Question 4

What's the correct install order? LineageOS (microG fork), then Magisk, then Asus Camera?

Question 4b

How do I deal with the A/B thing?

Do I have to install everything to both partitions, or does the recovery install to both partitions automatically, or is stuff installed to just one partition and then somehow magically handled with the next update?

In particular, how do I get Magisk and Asus Camera to carry over to the other partition?

The instructions for the LineageOS recovery include an extra reboot right after installing LineageOS so that the remaining stuff ends up in the same partition. Does TWRP also need the same extra reboot?

Question 5

Do I understand correctly that the GCam port is just a regular apk that can be installed later through normal means -- no flashing required?

Question 6

About divorcing the boot password from the lockscreen:

Does that post apply to LineageOS?

Does the A/B thing complicate the instructions in any way? It sounds like the files to be backed up and restored are in the data partition, so I'm guessing not.

Do I need to remove the boot password to make a recovery work? It sounds like the LineageOS recovery can handle the password; the unofficial TWRP can't even handle the encryption format; and the official TWRP is currently bugged and needs the password removed. Is that right?

Question 7

So, OTA updates for Lineage OS are a thing now? Could someone explain how that works?