For sure. I think I can do it with my desktop, if not, I can spin up my server. Sorry for the delay. Holiday crap and other issues.You should use the official Google device repo for A11, along with the minimal manifest for TWRP. Then just follow the same process as the bonito repo to retrofit it for TWRP.
The easiest way to extract blobs is to do so from the factory images.
EDIT: If I can find some time I may help with this, as long as you're willing to do the building and testing, I can probably create a mostly complete device tree for you to start with.