As a software guy how to a turn my collection of dev boards into a finished product?

You could hire someone on a job site. But they will expect to be paid at least a few $k per month. PalmPilot has not existed for about 2 decades but nowadays there are smartphones with a display and user input. I have no idea what your intended product is supposed to do, but I'd be surprised if it wasn't possible to at least partially design most projects that require a display and buttons, around a mobile phone app instead. There are many other devices with a display and a few buttons that might be adaptable with a firmware change, which might be easier for you if you're a software engineer instead of a hardware engineer.

"a job site" do you mean fiverr? be a little more specific.

You know of any Android phone that lets you send/receive custom packets of the cell radio?

Actually The retro handhelds are more appropriate than cell phones as, once to discount the Cell radio which you can't use the handheld they actually support custom firmware, but you still have the problem of how to add a LoRa radio.

"a job site" do you mean fiverr? be a little more specific.

You know of any Android phone that lets you send/receive custom packets of the cell radio?

Actually The retro handhelds are more appropriate than cell phones as, once to discount the Cell radio which you can't use the handheld they actually support custom firmware, but you still have the problem of how to add a LoRa radio.

By job site I mean any job site that is visited by engineers, and it might be a country-specific site or not, depending on what you're comfortable with. Examole: https://www.jobsite.co.uk/ (To place an ad to hire someone at that site, click on Recruiters, then click on Job Ad). 

"You know of any Android phone that lets you send/receive custom packets of the cell radio?"

I don't know what you mean by that, nor your precise requirements. All I'm suggesting, is that a lot of interfaces can be constructed with existing hardware, whether that is Android or not, so that if software is your strength, then you could reduce any hardware development effort to the minimum.

For instance, if I didn't have hardware experience, but needed a user interface, then I'd pick ready-made hardware and repurpose it. That's fairly easy to do with mobile phones using apps (native, web, etc), but it doesn't have to be a mobile phone. People have managed to write their own firmware onto Nintendo Game & Watch devices; they contain a display and a directional pad too. 

If one of your requirements is to attach LoRa, then that can be done with some hardware effort from whoever you hire, otherwise, there are ready-made LoRa gateways that accept Bluetooth connections (i.e. perhaps from a mobile app). I don't know if that would fit your requirements or not, since it's your project, you need to show your requirements to at least whoever you wish to do the work for you.