This video by Tony Northrup about Lightroom Mobile running on a 12.9" iPad Pro is worth 10 minutes of your time.
I have the older 12.9" iPad Pro (not the 2017 model) and the speed of Lightroom Mobile on it is truly amazing! I'm working at getting adept at using Lightroom Mobile and the pen. I'm having a hard time giving up the mouse. Tony makes it look easy.
As Tony says, Lightroom Mobil doesn't yet have all the features of Lightroom CC but it has enough to be very useful. There are even parts of Photoshop and Affinity Pro that provides layer features. The most important feature is that if you have Adobe Creative Cloud everything you do on Lightroom Mobile is synced to your laptop/desktop and vice-versa so Lightroom Mobile becomes an extension to Lightroom cc.