Form 8606

You should include ALL of your IRAs (other than Roth IRAs) on Line 6 of Form 8606.  That would include any 401(k) rollovers, and traditional IRAs, whether the contributions were tax deductibile or not.

Thanks for this. Just as a follow up, on line 2 of for 8606 then I should only include my non-deductible contributions as my "basis", right?

Line 2 is you basis from nondeductible traditional IRA contributions made for years prior to 2020.  Any amount of traditional IRA contributions you made for 2020 should be on line 1, not included on line 2.

On Line 6 should I include my 401K if it is still with my former employer although I am retired?

Nothing about a 401(k) goes on Form 8606.  A 401(k) is not an IRA.  When TurboTax asks for the year-end value of your traditional IRAs, include only your traditional IRAs, not the 401(k).