Summary
The Warriors were very high on Smailagic going into the 2019 draft, which has been well documented, but so far he has not lived up to the hype and the multiple picks that the Warriors used to move up to get him in the second round in 2019. Smailagic got some minutes during his rookie season when the Warriors were the worst team in the NBA, but even then wasn't too productive. Smailagic has spent most of his time in the G-League, and has not shown that he belongs on an NBA court.

Smailagic does have nice touch inside, as his field goal percentage on two-pointers is a solid 61.5% for his career. However, the Warriors hoped he would also be able to stretch the floor, and that hasn't been the case. Smailagic is a total 30/133, just under 23%, on three-pointers in 66 G-League games over the last three seasons. He also doesn't look very mobile on defense, and at 6'10" isn't a massive paint presence inside either.

Smailagic is still only 20 years old, and the Warriors may keep him around in hopes he can become what they hoped he would, but I think it's unlikely he becomes a rotation-level NBA player.
 
Cap Considerations
Smailagic's $1.8 million salary for 2021-2022 is non-guaranteed, and if he is waived he will become an unrestricted free agent and the Warriors will have no form of Bird rights on him. If he is waived, teams could claim him off waivers, but would need to fit his salary within cap space or an exception to do so, as his contract doesn't fit within the minimum salary exception as it was a four-year contract.

If Smailagic becomes a free agent, other teams will have multiple ways to sign him as even teams without cap space could possibly use either of the Non-Taxpayer MLE, Taxpayer MLE, or possibly even the Room MLE to sign him. However, I don't expect any offers for Smailagic to be above the minimum.