With all the hoopla about entering Phuket, there is a lot of misinformation online. Here are the official requirements for traveling from Abroad and entering into Phuket. It may seem like a long list, but the main thing is to be vaccinated. Everything else is similar to someone just entering another part of Thailand.
You should be travelling from a low risk country and be there at least 21 days before travel to Phuket.
Your must obtain the Certificate Of Entry (COE) to Thailand. Here's the website.
You must be fully vaccinated at least 14 days before departure. Children under 6 years old do not need the vaccine to enter Phuket.
You should have a negative Covid-19 Test and have the certificate to prove it from your doctor/hospital/testing facility, no more than 72 hours before departure.
You need to have insurance that covers Covid-19 for at leat $100,000 USD. Most travel insurance offers this these days. An example quote for World Nomads is about $90 USD.
Must stay at a SHA+ Hotel. This is simply a hotel that has been checked for the proper safety standards. Here is a list of SHA+ Hotels in Phuket!