@mezr , Having gone through your post , I still need a few more bits of info
(a) when you left the USA , how did you show your intent of not returning --- did you turn in your visa or your visa expired or ?
(b) are you a citizen of the country you went back to or is this a third country where you are now residing and working?
(c) did you own a home, bank account, kids in school in the USA - what we need to determine is the strength of your connection to USA after your departure from the USA.
Assuming that you can prove that you have left the USA on XX/XX/2020 and did not plan to return then the lack of "sailing permit" would really have no tax impact --- it is way to ensure that IRS has a way to collect axes due after your departure.
Dual Status returns can be mostly prepared using TurboTax -- I say mostly because the 1040-NR ( required for Non-Resident filing ) is not supported by TurboTax. Their partner SprinTax covers this area. If using TubroTax, you would have to prepare the Resident portion as normal ( note that because you are dual status , you would have to use itemized deduction - there is no way to apportion the standard deduction between Resident form 1040 and Non-Resident form 1040-NR. It may be more tax advantageous to file as a resident for the whole year ( this would mean that your foreign income during the rest of the year and the stock sales in Nov 2020 all come under the USA tax and you take foreign tax credit/deduction for the taxes paid to your home country).
BTW-- which country are you from and where are you working now?
You may also want to consider using the services of a tax professional familiar with international taxes and tax treaties.
If you need more on this, I would be happy to help
stay safe
