I don't think Democrats have high expectations right now. "Caretaker" government is how the more left leaning Democrats describe it. It's enough for now but 2022 is likely to be a tough election for Democrats.
https://fivethirtyeight.com/features/republicans-2020-gains-in-the-house-set-them-up-well-for-2022/
Biden is going to be in the hot seat regardless of how much he gets done. As you say, he has a pretty full plate. With the Senate in the hands of Republicans and an angry crowd of 70 million people who believe the election was stolen from them, it's hard to see how much he can do beyond stopping the epidemic and getting the economy started up again.
On a side note, while driving around town doing errands yesterday, I toured some right wing radio stations. There is a wall of noise coming from the radical right propaganda programs, all of it talking about a stolen election. Very loud, very consistent messaging that repeats the claims of fraud without any objective facts or evidence. This country has many more people who support radical right authoritarian leadership than I believed before the votes were counted. Just goes to show how naïve I am.
It's going to be a difficult 6 or so years, with control of our government flipping back to those same radical authoritarian Republicans some time during that interval. You might want to keep that border closed and be wary of signing treaties with the US.
But hey, today, we got rid of Trump, hold the House and assuming we lose both seats in the Senate to Republicans, we still gained a seat.
This is a win and winning is always better than what Republicans are choking on right now.