A lot of them are "optional" but strongly preferred. E.g. if one or two of the mirror wings failed to deploy, JWST would still be usable, but with a degraded resolution.
If one or two layers of the sunshade failed to correctly deploy, JWST is still usable, but the temperature of the mirrors would be higher than expected, and thus the spectrum of IR light it can image would be reduced.
If the momentum flap fails to deploy, then more fuel is needed to keep the JWST at the right attitude/position, shortening the lifespan of the mission.
But some others were make or break: deployment of the solar panels, deployment of the secondary mirror and a few others. If those had failed then the mission would be over.
If one or two layers of the sunshade failed to correctly deploy, JWST is still usable, but the temperature of the mirrors would be higher than expected, and thus the spectrum of IR light it can image would be reduced.
If the momentum flap fails to deploy, then more fuel is needed to keep the JWST at the right attitude/position, shortening the lifespan of the mission.
But some others were make or break: deployment of the solar panels, deployment of the secondary mirror and a few others. If those had failed then the mission would be over.