I reviewed and purchased a smaller drone, from WHISPR. Through that, I looked at similar VTOL drones, which OP is demonstrating. In theory, they're cheap:
https://www.uavmodel.com/products/makeflyeasy-hero-2180mm-ua...
This one has a maximum climb rate of 3 degrees. Which means you'd need to plan a route that's continously climbing, and tacking back and forth to avoid going steeply. So you would probably combine flight planning using Mission Planning: https://ardupilot.org/planner/ and custom json tweaking following MavLink protocol: https://ardupilot.org/dev/docs/mavlink-routing-in-ardupilot....
The open source flight controllers and systems are https://ardupilot.org/copter/docs/common-autopilots.html#ope... a good place to start. There's a few orgs building the full experience, but you'll of course pay for fully integrated, but still open source, hardware+software.
The scenario you describe is exactly what a VTOL or normal play is for; quad copters simply do not cover enough ground.
Also consider the camera. DJI typically ship with really low quality cameras, but https://www.bhphotovideo.com/c/product/1785754-REG/sony_ilx_... would get you a much higher pixel density so if you're more interested in the imaging, you can flight higher, near the licensed ceiling, completing more ground faster.
I've also found AI models know how to calculate pixel densities, so it's pretty easy to mock out a flight plan even if you dont have the actual drone available.
While that Sony piece of kit probably can do some cool things, 2950$ without objective/lens, seems rather expensive. Also 8.6 oz / 243 g (Body Only) don't look that light to me.
I'd probably go for some Sony Experia 10III[¹] or upwards, for no more than 300$ at 170 g (unmodified), and strip the hell out of it. Does it need a display, all the parts of the case, and so on? Can can I use its GPS, and pipe it into the flight controller, instead of having to rely on something more powerful and heavy, power guzzling?
[¹] because https://xdaforums.com/f/sony-xperia-10-iii.12225/
If you use ground control points, GPS accuracy isnt a bog deal, but im willing to bet the standard GPS puck still gets better.
I dont know much about the weights involved, but hardware surgery was not interesting to me.
Keepbin mind tge guys starting at DJI and youre proposing stripping dowm a camera
for processing, I setup opendronemap: https://www.opendronemap.org/
There really is a full open source hardware/software path, which is heartening.
This actually has decent flight time! Could probably push close to 3 hours if using higher energy density (and cost) battery cells like the silicon anode ones I used.