I can't predict the future, but based on salary cap, injuries, player age and contracts, etc, there is a high probability that the 2021 Bucs will be superior to the 2022-4 Bucs. This year is our best chance in the foreseeable future to win a Super Bowl (and a repeat would be awesome).
Based on this assumption, I'd be super aggressive this year and trade a second rounder for Gilmore. We can still adjust some contracts for cap space and would create plenty of cap if they'd take OJ in the deal.
Sherman fills a hole as CB2/3 to stabilize the defense. Gilmore (if he hasn't lost speed and is willing to play under his remaining contract) should elevate the entire defense by making Davis CB2 and possibly giving the front 7 an extra half second to rush the passer.
I'd love to prioritize fixing our pass rush, but I'm not seeing a realistic and impactful trade candidate there. Also, when Gilmore signs elsewhere in the offseason, we should get a 3rd round comp pick for 2023.