Offering Galvin 650k a season is just a waste of everyone's time. His manager would laugh in your face and if anything you'd have slightly increased his chances of leaving by offering such an insultingly low deal. The bidding for Galvin starts at 800-900k and that's for the two seasons he's already contracted; I'd be shocked if an extension to 2028 can be done for less than 3.8m. Don't think he's worth it? Your call; someone will.
There's also not as much coming off the books as you think at the end of 2026. Bird (dear god we gave him two years, SMH), Koroisau (but we'll need his money to keep Da Silva, hopefully), Olam (but the same applies re Makasini) and maybe To'a are the only ones who are on any real coin (and I doubt To'a is on much). The rest will all be close to minimum salary, which doesn't help as they need like-for-like replacements.