Net SE income: Roth 401k, IRA, and health insurance deductions

Let's say

• you have about $10,000 in net self-employment income (Sch C).
• your healthcare premiums are $10,000, and you're not covered by any other health insurance
• you're married-filing-jointly with a MAGI < $104,000 as per https://www.irs.gov/retirement-plans/plan-participant-employee/2020-ira-contribution-and-deduction-l...

Can you do all of the following?

• Open a solo Roth 401k and contribute $10,000 [presumably leaving S1 ln 15, the line for self-employed retirement plan deducitons, blank as it's a Roth]
• Also deduct $10,000 in healthcare premiums [S1 ln 16]
• Also contribute $10,000 to IRAs (e.g. $6k to yours, $4k to spouse), and if traditional deduct on [S1 ln 19]

It feels too good to be true...