[Lenovo ZUK Z2 (Plus) Questions & Answers] NaXal:
I have tried the PE (Pixel Exp) ROM and here my observations on that.

The Good

Extremely fluid. Performance is mind blowing. I have tried 3 Custom ROM so far (AEX, RR, PE) and PE felt the best performing in terms day to day device usage. Feels like PE is meant for Z2 Plus and vise versa. Everything works out of the box, GApps are preloaded, ROM is simple but very effective. All sensors, every piece of hardware included in the phone works perfectly. I never felt it was a custom rom, felt like meant for Z2 Plus.

The Bad

Not just just pixel, this is present in all Custom ROM for me and my device. I am from India, and using Reliance Jio VoLTE.

Now the problem is network reception isn't as good as stock ZUI.

The 2.4GHz WiFi got limited to 72 mbps only. Stock ZUI has no problem, tried changing few ROMs and finally settled with AEX which I see can connect to 2.4GHz WiFi and 150 mbps. I have tried baseband 1.76 (ZUI 2.5.104 ST India) and baseband 1.70 (Latest) for ZUI 3.5.3xx China. Nothing seems to help. Out of 4 ROM, Stock ZUI (2.5/3.5), PE, RR, AEX, only ZUI and AEX are able to give me a 150 mbps wifi link speed.

Now regarding the VoLTE reception. VoLTE works fine but network is fluctuating like hell. For me, the same is present in all three custom rom I have tried. AEX, RR, PE. Tried baseband 1.70/1.76 but couldn't solve it. There are no call drops but network isn't stable at all. Tested with Reliance Jio NetVelocity app for detailed information and it seems with none of the Custom ROM, Phone is able to sustain a stable 2300 MHz link. Falls back to 1800 MHz and 850 MHz randomly. Network speed wasn't bad, infact I would say satisfactory.

Only ZUI seems to have a stable Jio reception for me.

The Ugly

Battery issue. SOT is similar with 3 roms I have tried. PE/RR/AEX but something under PE is causing serious battery drain while idle. Overnight the phone is losing 2.5% to 3% battery per hour. I have tested to different custom kernel. AR-Beast and Heliox v2.0 with PE. Liked AR-Beast better as Heliox would underclock the CPU/GPU. Now with AR-Beast the idle battery drain came down to just around 1% per hour but still higher than default Resurrection Remix (RR ROM) or AEX ROM.

Presently using AEX ROM without any extra modification. Performance isnt as fuild as Pixel ROM but less problematic than others. Infact only ROM allowing me a 150mbps WiFi link speed.

https://xdaforums.com/lenovo-zuk-z2/how-to/z2-z2-plus-bootloader-unlock-twrp-t3615283

Follow this guide to unlock the bootloader and install TWRP. Then installation processor of ROM will depend on which ROM you select. Note, there are two different ROM type now. 1. Full Treble 2. Non Treble. Installation process are different for them.

Pixel is a non treble ROM. Like 2 years ago, you would feel similar setup process.

If you chose Pixel, after you have unlocked and got TWRP installed,

1. download PE ROM

2. boot into TWRP

3. Wipe system, data, cache, dalvik

4. Flash ROM

5. Wipe Cache

6. Reboot

If all went ok, frist boot will take a few minutes and you will be asked to setup your Google Account under Pixel Exp ROM.

Remember, I am not an expert so wait for others to comment and guide you !! Just sharing from my personal experience !!

Good luck.