My 2020 1040 has no line 8b. How else can I determine my AGI?

[fanfare]

Why are you looking for 8b?

Look for the line that says "This is your adjusted gross income"

If you used the non-filer's portal, enter AGI = 1.

[mesquitebean]

@ varnabulgaria201

On a 2020 Form 1040, the AGI (Adjusted Gross Income) is on Line 11.  

You were likely reading an old post from an earlier year.  The forms sometime change a bit (in some years a lot) from year to year.