Sorry for your loss. Yes you can file a Joint return for 2020. Just file as before with both your incomes. You can get the Stimulus payments. I think you will also the 600 for him too. There will be a screen asking for the amounts you already received.
@lumbee45 I am so sorry for your loss.
Since the passing of your husband was in 2020, you still can file as Married Filing Joint for the year 2020. Thereafter you are a widow ( essentially treated as single ) for tax purposes unless you have dependents for whom you maintain a household -- in which case you can continue to file as Head of Household.
Dose this help or is there more I can do for you ?