My previous experience on TWRP was on a Mi 9 with TWRP flashed directly to recovery partition, and installing Magisk had nothing to do with TWRP as I patch the boot image directly in boot partition.
I have been using Mi 11 with Magisk and without TWRP. MIUI EEA ROM. Because I want to backup my stuff, I am now trying to install this official TWRP, but have a couple of questions:
1. The instructions here seems to say I will need to "fastboot boot twrp.img" to get into TWRP, and then install permanently from within TWRP. Tried it, and the confusion came when it started to flash to boot partition instead of recovery partition. So it overwrote my Magisk patch in boot. No problem I thought, I would reflash Magisk (canary), but to my surprise only the 'patch boot image' option is available in Magisk Manager, and I couldn't figure out a way to download the .zip file to be used in TWRP to flash Magisk. Of course if I go ahead and flash the patched boot image in fastboot, then Magisk replaces TWRP. So it seems I can have TWRP or Magisk but not both at the same time. What step am I missing to try and make TWRP and Magisk (canary) co-exist?
2. I noticed USB-OTG support is missing. Back when I used Mi 9, my main action in TWRP was backing up directly to usb-otg, since my phone lacked spare space to store the generated backup file. Same case now for Mi 11 - if i run backup and pick internal storage, I won't have enough space. So how can I go about doing the backup if I cannot use my USB stick?