Your AGI should be visible in your Tax Timeline in the account you used last year. Though the Tax Timeline isn't visible in the mobile app, you can login to TurboTax Online through your mobile browser and access your Tax Timeline there.
If you have trouble finding it, an alternative is to request a free tax return transcript from the IRS at https://www.irs.gov/individuals/get-transcript
For more information, see our official FAQ about locating your AGI:
https://ttlc.intuit.com/replies/3301618