this is great advice. No matter how much you like staying in a foreign country, you can’t expect to have the same privileges as a citizen of that country because at the end of the day, regulations are designed to cater to your purpose of your temporary stay.
Therefore, it’s probably wiser to start anew by going back home. Home always sounds best.
If your son is half Thai and has Thai nationality you can apply for a non-immigration visa type O / year visa which allows you to stay in Thailand for longer periods. Once your visa is secured you can apply for other jobs or you might look into selling things online. There are some kind people around in Phuket I’m sure, perhaps you can get support to start a business of your own. All the best!
Yes the domestic postal offices are open in Thailand as usual. However international delivery can be delayed depending on the travel restrictions and limited flights between certain countries.