Hi @KiwiFire and welcome to the forum.
First and foremost regarding the Non Imm O visa.
This could be lengthy!
According to the Thai Embassy website in Wellington and confirmed by the e-visa application site, for your wife to apply for the Non Imm O to join non-Thai family in Thailand, you would already have to be residing in Thailand.
You would apply based on retirement.
Your wife would apply based on joining a Non-Thai family member already residing in Thailand.
The financial requirement for the Non Imm O retirement is the equivalent of 800,000 BHT in any bank account.
The financial requirement for the Non Imm O based on joining a non Thai family member is the equivalent of 30,000 THB in any bank account.
https://wellington.thaiembassy.org/th/publicservice/81086-non-immigrant-visa-o-other
This type of visa is issued to applicants who wish to enter the Kingdom for the following purposes:
- Non-immigrant O (Spouse/Family) - To stay with a family member who is residing in Thailand
- Non-immigrant O (Volunteer) - To do volunteer work with state enterprises or social welfare organizations in Thailand
- Non-immigrant O (Retirement) - Retirement / pension earners
E-visa website;
https://www.thaievisa.go.th/visa/non-immigrant-o
Staying with Family Visas
To stay with non-Thai family residing in Thailand (more than 60 days)
Required Document
( Please check relevant embassy/
consulate-general website for specific
required documents)
Biodata page of Passport or Travel Document
Photograph taken within the last six months
Document indicating current location
Financial evidence: an amount of no less than 30,000 THB (e.g., bank statements for the last three months, sponsor letter)
Personal details of a family in Thailand (e.g., ID card, passport and the visa page or stay permit in Thailand)
Proof of relationship to a family in Thailand (e.g., a copy of marriage certificate/birth certificate/certificate of adoption)
Number of entry single
Validity of Visa 3 months.
Single
3 Months
On entry to Thailand, you will be granted temporary permission of stay for 90 days.
Open a (Savings) account in your sole name and transfer the required 800K for Immigration purposes.
Once the 800K has been deposited for 2 months, but before the 90 days expire, you can apply to extend your permission of stay for a further 12 months based on retirement. The criteria to apply for the retirement extension, is subject to clause 2.22 of Immigration Order 327/2557.
Your wife would 'piggyback' your extension under clause 2.20 of the same order.
You can download order 327/2557 from this link https://aseannow.com/topic/981135-laws-regulations-police-orders-etc/ No.12 in the list.
Only you require the 800K, not your wife.
There are other points to cover, but let's walk before we run.
Have you been to Thailand before, and where would you intend to reside, as that will dictate which Immigration office you would use?