Sense, not nonsens(e), @BoRRoZ,
At the risk of expending energy sending information into a mismatched communications channel, I will leave it thus, in the hope that others in my situation might be helped. (Also, thank you, again, @marssystems for your considered, efficient, and informative response).
I have worked hard to understand this and, as far as I can tell, the previously referenced Microchip "LoRa Development Suite" is NOT intended for direct use with the stand-alone RN2903 (or RN2483), LoRa radio module (approx. $12 US). The development suite is intended for use over USB/Serial COM with the Microchip LORA EVALUATION KIT (~ $500 US !!!) or LoRa Mote (not module). The Evaluation Kit includes two LoRa Motes (RN2903 or RN2483) and a LoRa Gateway. This Evaluation Kit would NOT be necessary IF the radio module were well implemented and documented (a negative condition, IMO!).
If I am incorrect, spend the effort to graciously correct me, with detail (if you please).
My own custom board is similar to the the above MOTE but more lightweight.
As far as I know, my (or others') custom boards CANNOT BE UPDATED WITH A PROGRAM WRITTEN FOR THE LORA EVAL KIT OR FOR THE LORA MOTES, the latter of which communicate with the PC through a virtual serial COM port through USB.
From the following schematic in the RN2903 module (not mote) data sheet, we can see how to connect a PICKIT programming tool (~ $60 US) or ICD programmer so that firmware can be updated directly to the RN28903 module. This is the hex file that I originally asked for in this post.
The best I can tell is that the LoRa Evaluation Kit java webstart program (or applet) here will not work nor is it intended to directly flash the RN2903 module. That app is also a 200 Mb download of a .exe file (on Windows) that must be installed on (and pollute, in my estimation) my local hard disk when all one needs is a several kilobyte hex file that can be utilized in a common and free Microchip dev environment to update the RN2903).
With due respect and appreciation of much great work and assistance that has been rendered on TTN, I would also like to state an observation of TTN forum behaviour that I think can tend to devalue the excellence of this community:
This forum is a welcome and powerful IoT resource. However, rash answers here have, at times, tended toward having a signal-to-noise ratio of less than unity (i.e. post responses often contain more noise than information and can thus mislead and detract from open LoRa progress, obfuscate correct answers, and send forum participants on incorrect and expensive wild-goose chases). Please measure responses with a dose of self-assessment of the depth of one's own true knowledge. Efficient, precise communication and objectivity add value and are important in making engineering/scientific and IoT ecosystem progress. Less than this can actually do great damage, waste others' time, and decrease credibility.
With true respect for my techie family worldwide ...