Sanders voted against comprehensive immigration reform, and his M4A and Green New Deal proposals are so expensive and far-fetched that they are far less likely to get passed than the plans of other candidates. Meaning on all three of her issues, Sanders is the least likely candidate to actually enact positive change.
You really seem to think that when Cocaine Mitch tells him that he won't bring any legislation to the floor (and yes, he'd give the same treatment to Byeden, contrary to what you've delusionally asserted before), he'll just throw his hands in the air, give up, and do nothing, which is obviously BS.
Plus, we've said it before, and we'll say it again,
and we hope this is the last time we'll have to say it:
a lot can be accomplished by executive order (and Sanders would be willing to go further than anyone else in the field), and Trump has set a national emergency precedent.