No. 2 - Seattle should sign guard Kevin Zeitler
Seattle might need upgrades at every spot along its offensive line other than left tackle. Left guard Damien Lewis has been solid the last three years but he is a free agent. His contract might also end up being higher than Zeitler's because Lewis is only 26 years old while Baltimore Ravens free agent Zeitler will be 34 during the 2024 season. Zeitler's most recent contract did average $10 million a season, but I am not sure his future contract will.
Seattle also needs an upgrade at right guard as well. Phil Haynes is a free agent and there is no real reason to re-sign him. Anthony Bradford will be entering his second season but he might not have shown enough in his rookie year to prove he can be a long-term starter. Plus, he will have to show a new coaching staff that he was worthy of his 2023 draft pick.
Evan Brown probably won't be retained at center giving 2023 draft pick Olu Oluwatimi a potential chance to start. Oluwatimi did not get a ton of playing time this year, however, so he would basically be a rookie in 2024 in terms of reps. There is also no proof he will be a good center in the NFL.
I point the above out because Zeitler would not only bring quality - he allowed just 19 total pressures and 2 sacks in 2023 - but a veteran presence for what is probably going to be a young offensive line. Maybe Seattle drafts an interior offensive lineman high in the 2024 draft and that would add quality, but Zeitler might be the anchor to an O-line that features two third-year tackles, a second-year center, and potentially a rookie at the other guard spot.