Can I use regular income instead of 800,000 Baht in savings for a retirement visa in Thailand?

You can't use regular monthly wages from work it has to be retirement money or 18k it fosent have to sit in bank for 3 months they just want to see you have the correct funds in your account. This is UK

For the VISA, which is a 90-day non-O visa, that you get from an embassy, you can use either of these.

But for the first 1-year extension you get from an immigration office in Thailand, there are ONLY two options:

1) Proof of 800,000 baht in your Thai bank account

2) Embassy verified income

If your embassy in Thailand does not verify income (many do not), then your ONLY option is 800,000 baht in your Thai bank account for the first year. If you want to switch to the monthly transfers option, you have to start planning over a year in advance and starting monthly international transfers of at least 65,000 baht every month.