Is FileMaker Go supported?

Yes - fmSMS supports FileMaker Go 16 or later for iPad and iPhone. 

When you open fmSMS with FileMaker Go you will navigate to specific layouts for your iPhone or iPad. We’ve added support for viewing Contacts and sending Messages with FileMaker Go – additional support can be easily added as required, for example to view Replies, Delivery Receipts or send a bulk SMS to a found set of Contacts.