A helpful person with access to several new phones has sent me debug logs and success/failure reports. Thanks !
These are all stock and unrooted.
Galaxy Note 3 LTE SM-N9005: No stock FM app included and Spirit won't run. Uses a Broadcom combo chip. When rooted I'd bet I find the FM antenna pin is grounded, same as on all GS4 variants.
Sony Xperia Z1 Honami: Works fine with Audio-> Method set to "Sony Z...".
Sony Xperia Z Ultra: Works fine with Audio-> Method set to "Sony Z...".
HTC One Mini: Works fine.
Also I've seen Xperia M works, but not sure about audio yet. Uses Qualcomm OEM API, but Qualcomm low level may also work on stock, unrooted, as well as "STE/Android" API.