I assume the intent is that either the answer is both yes or both no. But strictly reading it RAW, I can see a case that they may have different answers.
Step says:
Stepping doesn't trigger reactions, such as Reactive Strike, that can be triggered by move actions or upon leaving or entering a square.
To me, there is a good argument to be made either way, that Ready has a trigger the player sets, and thus it is not prevented. Or that they have chosen the trigger to be "a move action", and thus it is prevented.
Mobility says:
When you Stride and move half your Speed or less, that movement does not trigger reactions.
This is much more black and white. RAW, you cannot Strike someone who Strode less than half their speed.
I’m curious about whether you agree with my RAW interpretation, but even more about whether you think this is intended. And thirdly, if it is intended, whether you think it’s reasonable.
I’m not sure about the second question, but on q3 I definitely think it’s reasonable. Spending 2 actions and your reaction to get just one strike in. From action economy it sounds fair to me that this would bypass Step and Mobility. And from a flavour perspective it also makes sense to me, because a normal Reactive Strike is just quickly taking advantage of an opening they provide, but a Readied Strike is more like heavily concentrating on and waiting for a specific situation, which they shouldn’t be able to avoid just because they only take one step.
Opinions?
I agree that for action economy reasons it makes the most sense to allow Ready to bypass the more generic doesn't trigger reactions text. The open-endedness of Ready trigger I think would also support this. You don't need to specifically identify movement, stride, or any other keyword the way other reactions do.