I don't see a way to transfer last year's return from TaxAct to TurboTax online. There are some instructions, but there is no place to upload the pdf file.

A pdf will do so little it is not even worth the trouble.   A pdf will only put in some of your personal information like name, address and SSN.  You can easily key that stuff in for yourself.   A pdf will not transfer employer information, etc. etc.

In addition to importing personal information, I expect TurboTax Online to show side-by-side comparison of last year vs this year if it has previous year's data. I am using TT for the first time and loved that feature of TaxAct.

Transferring from a pdf file is limited.  And you can't transfer from a 1040SR pdf.  You should try to Transfer from the .tax file.  Here's a couple links to explain more.....  https://ttlc.intuit.com/turbotax-support/en-us/help-article/import-export-data-files/transfer-last-year-return-2021-turbotax-windows/L0JcyjyrG_US_en_US?uid=lqyfj3a8

PDF vs .tax file

https://ttlc.intuit.com/turbotax-support/en-us/help-article/data-systems/difference-tax-data-file-pd...

https://ttlc.intuit.com/turbotax-support/en-us/help-article/import-export-data-files/transfer-last-year-return-2021-turbotax-windows/L0JcyjyrG_US_en_US?uid=lqyfj3a8