To get who? Anyone available or quasi available Like Lindor, Betts are heading into FA after next year. That leaves DiDi and Grandal, and plenty of suitors.
$5.5M isn't really more than players like Galvis will get. The Nats signed Brian Dozier to a 1 year $9M deal last year, and he was coming off a lesser season Galvis is this year. Jonathan Schoop, $7M. You may not like Galvis, but he's a better defender than both those guys. He hit a combined .260 .296 .438 .734 which was better than both those guys, and they were two of the better MI FA's last year.
Also, It's like day frickin 1. An option picked up today doesn't mean anything more than he's on the 40 man roster. He can be dealt. He can be depth. Or he can be the starter at SS.
In 2019, Galvis had the 7th most HR's in all MLB at SS, 16th best OPS. No one ahead of him on that list is a FA. No one ahead of him on that list is available, so far, via trade. You've clearly made a case you prefer a better player. Can you state who you think the Reds could have gotten had they not picked up his option?