I made a Nougat build for this device (flounder) and for the flounder_lte.
Why Nougat ? Because it’s officially supported by LineageOS, and not Oreo so at least there is one build for this device we are sure it works correctly. But try the Oreo build first.
I just compiled my own ROM for flounder wifi. I have tested it and it works perfectly, except for sending screen (I think this happens with most Custom ROMs).
I have compiled the oreo version, because there are sources in LineageOS with that version (15.1). In fact, there are sources in LineageOS for the pie version (16.0), but it fails me with sepolicy and I can’t fix it.
I advise not to use TWRP 3.4.0.0, instead use the previous version 3.3.1.0
The structure of the roomservice.xml is as follows: