Can I continue my volunteer commitments while applying for a retirement extension in Thailand?

IN THEORY, if you meet the requirements for a yearly extension of stay based on being over 50 (retirement) you COULD change the reason for your extension (the one that's expired) from volunteer to retirement without ANY new visa by just meeting the requirements for the retirement extension (800K baht in a thai bank account in your name only for 2 months before you apply for the extension)

Even though the extension you were on expired the amnesty allows you to still apply for a new extension as if it weren't.

GO to the immigration office and see what they say

and for right now, let's keep the "can we still volunteer" question off the table, let's FIRST find out IF you can get retirement extensions inside the country before amnesty ends so you don't have to leave the country on the 26th.

Okay, lets sort this out, You DID have yearly extensions right?

BUT

they ran out back in June putting you on amnesty right?

Legally, you need a work permit to volunteer. On an extension of stay based on retirement, you can not get a work permit, and therefore can't legally volunteer. I would talk to your volunteer organization for their opinion on the options.