Though I like the spirit and intended message, so I don’t want to be too negative, I’m not personally too fond of this approach. Like you said, everyone can make their own considerations; I’ll add mine in case you find them interesting.
A big obstacle that often comes up with joint European plans is that every country wants their own local companies to benefit. This has long been a problem with defence (though hopefully a bit less so now), everyone wants to do a little bit of everything, which often ends up with them doing it poorly, while the EU also misses out on the benefits of scaling up. Or from the perspective of consumers, it’s why we don’t have a proper European alternative for Netflix, but instead dozens of “meh” national subscription services. For food, it can be complex; on the one hand it’s good for the environment to reduce transportation emissions, on the other hand, transport is often a negligible part of the emission cost of produce compared to other factors (but not always). So it’s often better to import produce from countries where it grows well, than buying locally from producers who use costly (financially or environmentally) methods.
It can get quite complex quite quickly. I’d say let’s consider local products as good options with potential advantages and disadvantages, but don’t necessarily view them as superior to other EU products. And let’s avoid falling into the trap of expecting direct national benefit from every individual EU initiative (not saying you specifically OP, just a general point).
While nice, this seems at odds with the budget cuts to science that are horribly undermining our existing, high-quality scientific institutions. It would be much nicer if luring these US-based scientists were an addition to a larger package to invest in, rather than cut and destroy, science in the country.
We could certainly use the help, so they’d be very welcome, but if we’re still getting rid of hundreds of fully set up scientists while gaining a few new ones from this, that’s still a net loss…
Plus, any US-based scientist who might consider doing this would surely look at these budget cuts, see how countries like France and Germany are actually investing in scientific infrastructure, and take this into account when selecting a destination. If you want to “lure” people over, you do need to have an actual high-quality and functional system to show off.