I was just looking to see what FAs are still available. It's actually a really impressive list:
Here's a quick link:
2021 NFL Free Agents Tracker
A few names that jump out to me:
ILB Kwon Alexander (27)
DT Sheldon Richardson (31)
DE Justin Houston (32)
DE Ryan Kerrigan (32)
S Justin Simmons (28)
G Trai Turner (28)
DT Olivier Vernon (31)
CB Steven Nelson (28)
ILB Avery Wilson (29)
OLB KJ Wright (32)
CB DJ Hayden (31)
T Alejandro Villeneuve (33)
S Kenny Vacarro (30)
S Trey Boston (29)
S Malik Hooker (25)
That's kind of a crazy list of players that can make valuable contributions.