In theory, this is a good idea, in my opinion. In practice, Stack Exchange websites do not seem to like or want to collaborate with each other (at least, this is my impression).
Why? Because I tried to do something similar in the past (like publishing links to some of the interesting posts on our site on their chat rooms or stating that RL questions can also be asked here and, in some cases, I said "should be asked here" because RL is central to AI, in my view: this "should" was probably what scared or made them angry, because RL is also on-topic there...), although without officially asking them (which was probably a mistake), but the guys at Cross Validation Stack Exchange didn't really like my actions, given that, in my view, they feel threatened that this can reduce their number of users and some of them would argue that our site shouldn't exist because they already cover a big part of our scope, which is true, although our site also covers topics that they do not cover and we focus on Artificial Intelligence and not Statistics, that's why we exist, I would say.
In any case, this is something that should also be asked on their metas to really understand what the status/consensus is now. In my view, collaboration can only help us and them. However, to be honest, I will not invest more of my energies and free time on these debates with them because I already lost too much time and effort in vain (but I admit that my approach in the past was not ideal and diplomatic, to start with, and that might have contributed to the unsuccessful attempts to try to attract more experts and users to our site). This does not mean that you or others can't try to do that by starting with asking the same question or proposing the same idea on their metas.