When $snallstartup I was an employee at got acquired by $hugemultinational, all we got was a big fat juicy 1000$ „bonus“, an attaboy, and those who had been grossly underpaid for years were brought up to market pay. And that’s it.
And "market pay" being HR's idea of the going rate, not what a good engineer with niche knowledge and startup experience could command at a big tech company.