Wait for sept 1st when those vaccinated can enter with no quarantine *(except from a few countries and pending cabinet approval). This is according to Quarantine Progress Plan to bring tourists back.
Yes.. I'm a grandmother many years on Samui. Loved helping raise my grandson here. Retirement Visa.. main requirement.. stated funds in Thai bank 2 months prior to applying for Visa. All documents carefully collected and ready. Your son or a visa service can help you with forms. See online requirements. Your income/ savings outside of Thailand does not count.