If they can spend on WR at all, keeping Lazard would be my preference by a long shot.
The only other FA I find interesting is Jakobi Meyers. However, if he makes it to the open market, he's going to get way overpaid because the demand is going to outstrip the supply at WR. And while I would be happy to have Meyers on the team, he would be a progress-stopper in front of Doubs as they would play a similar role in the offense. If you're running it back and going all in, you don't let that stop you. But Lazard's role as a power slot, especially in condensed sets, isn't redundant to anyone else on the roster.
That's a good start. Add another weapon, preferably one with who can threaten in motion and after the catch, and I think you've got a good, diverse corps.
At tight end, the options aren't amazing, but they're better. If Lewis wants to come back, I do that. And then here are the names to watch:
Y Tight Ends; In-line blockers who are good enough to block play-side (rarely split out)
-M. Lewis, Green Bay, 38
-A. Shaheen, Miami, 28
-J. James, Cleveland, 28
F Tight Ends; Primarily receivers who play heavily in the slot (usually split out)
-M. Gesicki, Miami, 27
-E. Engram, Jacksonville, 28
-I. Smith, Minnesota, 24 (H traits as well)
-R. Tonyan, Green Bay, 28
U Tight Ends; Dual threat in-line tight ends who aren't good enough to block play-side (can still split out)
-D. Schultz, Dallas, 26
-F. Moreau, Raiders, 25
-H. Hurst, Cincinnati, 29
-A. Hooper, Tennessee, 28
I'm sure there are more who belong on these lists, but I'm not familiar enough with them. Irv Smith intrigues me, given how young he is. Foster Moreau is also a guy who I think could be a better version of Robert Tonyan.