For the year of 2020, you are a resident and should file a Form 1040.
For 2019, technically speaking, you are considered as a nonresident as you did not meet the Substantial Presence Test SPT. As TurboTax does not cover nonresident filing, you are advised to contact Sprintax. This is probably the simplest way to go. However, you could file as dual status if you meet the First Year Choice. This way, you would file as a nonresident for the period before you entered the US and a resident from September till December.
To read more about the pros and cons on dual status, click here: Dual status
For instructions how to file Dual status, see DualStatus under "What and Where To File for a Dual-Status Year" and 1040NR.
If you have filed a Form 1040 for 2019, you would need to amend.
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