My experience so far. Quite easy, no worries (Oct 2021)

I am returning to my condo in Maho for the first time in over a year.

I am flying direct on Sunwing Oct 7 from YYZ Toronto an I am fully vaccinated.(Pfizer) Here is what you need to know.

To enter SXM from Canada as of this date (things can always change) you will require a Rapid Antigen test completed within 48 hours of departure.
There are several options for this test here in Ontario. I chose Shoppers Drug Mart. Just walk in and takes about 20 minutes to get printed results. Check with the specific location to get times etc.
I am traveling on Thursday so I got my test done at 4pm Tuesday. Cost was $40 CAD.

EHAS (Electronic Health Authorization System) for Sint Maarten. You must upload your proof of vaccination and negative Rapid Antigen test to the Sint Maarten EHAS along with the usual Passport information and where you will be staying. To complete filling out the EHAS system takes roughly 20 minutes. If you are from Ontario you upload a copy of the record of vaccination showing you have received 2 doses and the printout of your test results from Shoppers Drug Mart..Once you have completed filling out the EHAS it will prompt you to buy COVID insurance for $15 USD. VISA or Mastercard for the payment. Once you have paid you are finished. You will receive an email from them indicating they have received you application for review.

EHAS was submitted Tuesday at 5pm. At 8:30pm (same day) I received my Pre-Approved Authorization email. I received along with an email a PDF file which has my info and a QR code. Keep that electronically but also print it off in hard copy for customs. You will also receive a PDF file for your COVID 19 insurance. A portion of the insurance print out includes a card with a QR code. Cut it out and carry it on you.

You are ready to go to SXM.

I know it is a digital electronic QR code era where we keep everything on our phone but it is a good practice to print and have hard copies with you.

I have not done the return as yet but when returning to Canada, they require an RT PCR test (not the Rapid Antigen test) to return back into the country which must be completed no greater than 72 hours prior to departure. There are several options for getting the PCR test on the island which have already been covered in previous threads. Current prices range from $75 -$150 USD

Enjoy you trip to SXM.

Cheers DrPhilSXM