The post I have just added might help.
Oval chain rings may affect readings but only for some power meters. Since the Neo measures at the hub it will not be affected but the numbers you get should be less than if you had a crank or other power meter that did not factor in drive train losses.
The article below gives a bit more on this but is no longer up to date in one respect in its quote below.
“Here’s the concern: most power meters make the assumption that your pedaling velocity is constant.”
This may have been true in the past and may still be true for cheaper meters like the 4iii. However other meters are much more sensitive and sample the stroke many times during a revolution. So you really cant say “most” but “some”.