@User: I know several people doing rad-hard/rad-tolerant/extreme environment design (at JHU-APL, NASA GSFC, and Ozark-IC), and I used to do some of that myself when I was working at JHU-APL. So magic's extraction engine can properly extract annular MOSFETs. The problem with the annular FETs is a combination of rule X.2 (only 90 degree bends on poly except for specific vendor-approved cells) and rule poly.10 (no 90 degree bends on gates). This leaves open the possibility that you could make an octagonal annular FET and get SkyWater to approve the use of 45 degree poly shapes on the gate. Possibly they would allow a standard square-ring annular FET. At any rate, Google wants to push the boundaries, and that definitely fits the bill, and I'm willing to go haggle with SkyWater over waving certain rules to make it happen.

Thank you very much for the prompt reply.