[OnePlus 6T  ROMs, Kernels, Recoveries, & Other Dev] Terminator.J:
Installing/updating guide:

So for anyone, whether dirty flashing or clean flashing, this should be your process the first time coming to the new v7.4 from anything earlier:

- First, download & set up the things you'll need on your computer:

- Latest platform tools installed: https://developer.android.com/studio/releases/platform-tools.html

- Latest full OxygenOS OTA installer zip: https://www.oneplus.com/support/softwareupgrade

- Latest TWRP installer zip and fastboot-bootable img: https://twrp.me/Devices/OnePlus/

- Latest Magisk v22 installer (release, beta, or canary): https://github.com/topjohnwu/Magisk#downloads

- Latest GApps or microG installer that you're using. I've heard NikGApps works well and would recommend using the Core package and installing any other Google apps from the Play Store. I use MinMicroG - Standard package and recommend it over nanodroid for microG.

- The crDroid v7.4 zip: https://crdroid.net/dl.php

- Next, to be on the safe side, remove any device security for now (delete fingerprints, faceunlock data, change to swipe-to-unlock to remove your PIN/pattern), and clear cache/storage for the Settings app itself.

- Reboot to bootloader, make sure USB cable is attached, open a terminal and "fastboot boot twrp.img" (replace "twrp.img" with the name of the downloaded .img file from the TeamWin site) to start up in TWRP.

- Once booted into the downloaded TWRP 3.5.1_9 or later, copy the OOS OTA zip, crDroid zip, TWRP installer zip, Magisk installer zip if you use it, and whatever GApps/microG zip you use (or none!) from computer to internal storage (I make an 'Install' dir, but you can use Download or Documents or just copy to root; this is your world so you can put your happy little zips wherever you like. Thank you, and God bless.)

- We need to update to the latest OOS firmware at least once for each slot (you will get boot loops if you're using earlier than 10.3.8), and I know it takes forever, but at least you'll only need to do it twice (once per slot). Choose "Install", then select the OxygenOS full OTA zip (10.3.9 or higher as of this writing).

- You can stack installers that write to the inactive slot, and they'll all write to the correct place (slot change doesn't happen until reboot). Now select "Add more Zips" button, and select the crDroid installer .zip.

- Select "Add more Zips" one more time and select the TWRP installer zip.

- NOW "Swipe to confirm flash" and go get lunch or something; that OOS install takes FOREVERRRRR.

- Do not reboot to system yet. Press the home button, select "Reboot", then select "Recovery" to reboot to recovery in the other slot.

- Select "Install", and select the Magisk installer (TWRP 3.5.1 can directly choose .apk files that are also flashable .zip files, like the way Magisk is doing it now in v22 and above; cool huh?) if you're installing Magisk, then choose "Add more Zips" and select whichever GApps or microG you use (if you want to install one).

- Swipe to install, then be sure you choose "Wipe Dalvik" after it's done installing (or go into the Wipe menu and manually choose to wipe Dalvik if you're not installing Magisk or GApps/microG).

- NOW you can reboot to System, and enjoy!