My understanding is that certification is the bottle neck, in both time and cost. No one wants to spend the money or time to flight certify something new when something already battle tested will suffice.
But your comment makes me wonder if the private sector doesn't have those certification requirements?
The other differentiating factor is that the private sector is not sending multi-year (indeed multi-decade) deep space missions, where the need for battle tested systems is paramount.
Flagship multi-year science missions are generally conservative with technology choices, but some NASA projects are intended as technology demonstrations and can on take more risks.
So like the Perseverance rover on its way to Mars is powered by redundant RAD 750s (same as Curiosity), but the Ingenuity helicopter along for the ride is powered by a Snapdragon 801.
It depends on where the spacecraft is going as radiation environments differ. I've taken parts to be exposed by a proton line at a particle accelerator. For some environments they just use Cobalt-60 as a radiation source.
This reminds me of a relevant anecdote: back in the naughts, I was doing research in cosmic rays at a large nuclear research facility. I did simulation and data analysis - office/computer work mostly. One day, a person with a clipboard comes into my office and asks about the whereabouts of some radiation source. I look at them confused - I had not touched sources since teaching nuclear physics labs. They show me their clipboard and lo and behold, it has my name next to a really high intensity source and they're looking to locate it.
After a few minutes of awkward shock and denying all involvement, we realized it was a colleague at the same research institute (and of the same name). He was, one building down, doing his PhD research on radiation hardened detectors for the CMS experiment at CERN(1). He was using the source for the testing. But I had a minute of real stress before that came together in my mind...
To answer - no we don't have the same certification requirements. NASA steps in when there's human lives and/or a lot of money on the line, but most smaller projects and just about every independent project is free to assume its own level of risk.
You know (and probably are implying) this but it’s completely program/project specific. Some projects out of Armstrong, for example, must meet FAA certification requirements
But your comment makes me wonder if the private sector doesn't have those certification requirements?
The other differentiating factor is that the private sector is not sending multi-year (indeed multi-decade) deep space missions, where the need for battle tested systems is paramount.