If you want a cheap tablet you can use the fire 8hd. You will have to tweak the settings a little to get it to display in tablet more instead of phone, but works nicely for me.
just wiped and reset my Pixel C and it’s running Roon as a pinned app setting it as a fixed single use device. So far this looks like a great option for my big listening room. When at the computer things are pretty readily available.
I have the roon app up and running on an old Google Nexus 10 tablet (Android 5.x) which was completely wiped before installation. Everything seems to run smooth so far except the playback of Audio on the tablet itself (dropped the connection after a few seconds).
I also tried the app on various android phones available at home: Sony Xperia Z3 compact (Android 6.0.1), Huawei P8 Lite (Android 6.x). We used the P8 Lite as “private zone” for playback with headphones… worked nicely for my daughter 
As soon as I have my final installation ready I will try the app on my Samsung S2 tablet and a Honor 6X phone.
Been working great on mine for the past 2 years
I just got a Samsung Galaxy S2 Tab and have a graphic error (white fickering line) on top of the screen in landscape mode. Any tips?
Thanks