Smart phone light meters have been, in my experience, not very reliable. One reason is they typically cap at a pretty low measurement (sub 50k for sure) and are really meant for much lower indoor light situations, especially the front camera meter. Further, any measurement of "par" is almost certainly just a conversion from lux for some standard light spectrum. I would not trust it for much if you are outside of a "standard" spectrum.
Oh you don't know what "Standard Spectrum" means? Yeah me either lol. Hence why I don't put much faith in them.
If you care, you can chase down papers from this on the subject:
https://www.waveformlighting.com/horticulture/convert-lux-to-ppfd-online-calculator I think. Maybe it was a black dog whitepaper. Whatever, it's find-able.
If you want a good primer on cannabis and light, then I recommend Bruce Bugbee on YouTube.