There are no preposterous requirements for citizenship, that's a bar stool myth.
Not even a requirement to read/write/ speak Thai now, if married to a local.
Easy if married to a Thai. I applied Dec 2017 and got it Dec 2020, with delays for Covid.
I worked as an English teacher for 3 years, paying tax on 40,000 baht a month.
Anyway, I call myself an expat, not an immigrant, but won't go into why.