The DoD has a list of approved drone companies now. Some have similar features of distance sensors and such. Others try to cut costs a bit or put the money else where such as nicer motors or better GPS. Some of them even run the open source autopilot Ardupilot. https://www.diu.mil/blue-uas-cleared-list
If those DoD options don’t seem to be the right fit, there are still many commerical off the shelf options that use Ardupilot (no calling home at all) or PX4. No calling home, and (with Ardupilot at least) you’ll be able to update the firmware on your own. This can gain you bug fixes and new features without waiting on the company.
If those don’t seem to have what you are looking for, we’re down to DIY! Which is fun in its own way. There have been a ton of advancements in the DIY space since DJI became more mainstream. Lots of cool frame options and some very powerful processors by comparison to DJI.
I’ll leave a link to the Ardupilot and PX4 docs which list a lot of information about the last 2 options. https://ardupilot.org/copter/docs/common-rtf.html https://docs.px4.io/main/en/complete_vehicles/
GPL says you can sell the software for whatever price you want too. I could take any piece of sodtware licensed under GPLv3, bundle it up, charge people for that software (while telling them that what I am selling them is GPLv3 software and informing them that they can request a copy of the source code including any modifications that I have made to it). That’s totally fine. But why would someone pay for the software if the seller is not adding any value to to product? cough windows app store cough