Teensy is made for DIY electronics, mostly focused on makers & hobbyists. PJRC strives to keep Teensy's price reasonable, even though it's built in the USA and tends to compete against very aggressively priced products like ESP32 and Raspberry Pi. Quite a lot of work goes into each Teensy model to fit as much functionality as possible into the small "Teensy" form factor. Use of BGA and QFN chips is essential to meet those physical size goals.
We go to great lengths to make a Teensy a high quality product. But product design decisions are a matter of trade-offs. We try to keep the price price reasonable, which means the PCBs and PCB assembly & inspection of both are done to IPC class 2 specs. If you are concerned about the reliability of BGA packages (which have been in very widespread use for many years with excellent reliability), your application almost certainly would require IPC class 3 circuit board manufacturing and PCB assembly, is dramatically more expensive, and maybe even materials and inspection exceeding class 3 requirements?
https://www.acdi.com/ipc-class-2-vs-class-3-assembly-processes-what-is-the-difference-part-1/
Many people & companies do embed Teensy inside commercial products. But that's not Teensy's main focus.
If you need a high reliability (presumably IPC class 3) non-BGA circuit board, you're going to have to roll your own. We well MKL02 or MKL04 chips which you can pair with the MK66 processor in LPQF package to make your own PCB - but still leverage all the Teensy software.
https://www.pjrc.com/store/ic_mkl02.html
If you scroll down on that page, you'll see a reference PCB using the LPQF MK66 and TQFP MKL04 chip. That PCB alone probably does not meet all IPC class 3 requirements, like "teardrops" on all vias. It's meant only as an example and demonstration (and it's how we verified the larger MKL04 truly does work....)
I'm sure this isn't the answer you want, but it's the best & most honest answer I can give. I hope you can understand that we make Teensy primarily for makers who desire the most capability in a small size board at a reasonable price. Use of the huge LQFP package and other high-reliability (high-cost) measures that you're seeking would be awesome, but the large size and high price of such a board just would not be commercially viable in this maker market.