if US wants to put pressure on and punish China, then instead of shooting itself in the foot and everywhere else with tariffs US could have just offered say 10K Green Cards (each coming with $1M resettlement bonus) to the top China researchers&engineers in any industry in China that US would want to cripple as a punishment. At $1M per such a top head it would be a steal for US, and for China it would be a very painfu…
First, anecdotally, I've known a number of Chinese-national but US educated persons, who after receiving their higher education and 5-10 years of work, returned to China. The main reason being the "bamboo ceiling". Often, returning means accepting a lower salary but with higher career trajectory and a more peaceful life. I don't think throwing visas + cash at researchers (at least those I've worked with) would alleviate all the cultural problems that lead them to return home in the first place.
Secondly, a recent push for change in Visa distribution (S.386)[1]. Would make it extremely difficult to attract talent. As this bill stands it will significantly harm prospects of Chinese applications for EB2 visas. The kind of change being suggested here (recruiting researchers and engineers) falls into the EB1 - EB2 category. Given how difficult it's been to even get a bill changing pool statistics this far, I doubt you'd be able to do anything of the nature you're mentioning.
[1]: https://www.congress.gov/bill/116th-congress/senate-bill/386