If he can’t compete for playing time at quarterback with the Dallas Cowboys where can he compete for it?
There are always a couple teams each year with that QB black hole, sort of like the Raiders were in this year. This year who knows, there are a lot of bad teams who will be looking at QBs in the draft and someone is likely to miss out or get stuck with a guy they need to sit for a year (Giants, Browns, Jets?, Titans?, Raiders, Panthers?, Seahawks?, maybe a couple others?). I would bet someone out there would take a gamble on a brining Lance in to camp even if its a long shot type of situation. They could give him a min deal with incentives if he can actually win a job.
The other side to this is that even if he cant get a starting gig he probably is more likely to compete for a backup gig with a team like Indy, Baltimore, Washington, philly etc that already runs an offense with a lot of RPOs and designed QB runs to fit his skillset a little better.
I just don't think he stands a chance in Dallas at this point in any capacity. No one is knocking off Dak for the starting role for at least another year, likely two at minimum. You also don't want a QB like Lance as your #2 who is going to completely require a different offense if Dak goes down for a couple weeks.