[OnePlus 6 ROMs, Kernels, Recoveries, & Other Devel] Terminator.J:
Once I got it to install & boot in the first place, I have been flashing updates to both slots (flash rom, flash mauronofrio's twrp 3.3.1-14 .zip, reboot recovery, flash rom, flash twrp.zip, reboot recovery back to slot A, install gapps, install magisk, reboot system, continue life as normal) and it's been pretty painless. I've been using the Radioactive kernel (and recognize that it's at my own peril to do so) that's in the cross-development section and it seems like I finally have battery life back to how it should be.

I'm also weird, but I've been using bitGapps (again, realizing that it's at my own peril) (the package without Setup Wizard - the one WITH setup wizard was going into boot loops for me) since it has battery optimization/doze enabled for Google Phone Services, which also helps a lot for battery and I don't need the notifications IMMEDIATELY immediately for Gmail. TheHitMan has a new package out, v.6, and I haven't tested that yet. But at any rate, battery life has been nice that way.

This is an unsupported configuration and I fully recognize that I'm off on my own by doing it, but battery life has been great. Most of my contact/calendar/email sync takes place with a private Nextcloud server and not Google anyway, and most of my email accounts are set up in K-9 Mail rather than the Gmail app, and I don't use Assistant, so having GMS take a nap works well for my needs.

Magisk modules, well there's the built-in systemless hosts one for ad-blocking, which presumably works because AdAway doesn't complain at me and works fine. Other modules:

- BusyBox for Android NDK by osm0sis - because there's other terminal-based modules I like that require a functioning busybox and this guy makes all the best tools.

- Font Changer by John Fawkes (requires busybox, see?) - yay I want a different system font. Almost works with Android 10 but you need to do the last copying step by hand with a root-capable file explorer because Android 10 permissions. Leave any system font settings on Roboto, because this uses Magisk to overlay replacement font files for Roboto.

- MagiskHide Props Config (requires busybox!) by Digeridoohan - Well-maintained terminal-based module that helps overlay device fingerprints and other prop values to make sure you can pass safetynet and give you "Device is certified" in Google Play Store settings, because not every ROM developer has the time to worry about making sure we can play Pokemon Go out of the box. Better than the stupid "SafetyNetFix" one someone keeps recommending that is hard-coded to turn whatever device you have into a Huawei K20. For our OP6, you should choose the OxygenOS Pie fingerprint, because OOS 10 hasn't passed CTS testing yet.

- Global Optimized GPS File Replacer by ianhughes74 & lazerl0rd - the GPS file that OOS ships with is kinda crap; this tends to get me a fix much faster where I live (Seattle, WA, USA) so I'm not sitting there waving my phone around like an idiot while running to the bus stop.

- And substratum installs one automatically if you use it and give it root access. I like themes, and since (for the time being) AOSP (and hence Omni) and Google Pixel-themed apps don't understand that AMOLED backgrounds should be BLACK (#000000), not grey, and the accent color choices that come with continue to be hot garbage, I use overlay themes to be able to consistently turn backgrounds to black, with real red (not pink, not fuchsia, #FF0000) red accent color, the way God intended.

There ya go. I'm having trouble with two SIMs not being handled well, and in general I think I'm gonna go back to a Pie rom until OnePlus gets their **** together with releasing an Android 10 vendor and kernel/blob dump that isn't a dumpster fire and rom developers get a chance to build something useful on it. But for the most part, Omni (especially with bitgapps Q and radioactive kernel) has been the best of the best for Android 10 on OP6 in my testing. Kudos to darkobas and Omni team.