I applied for a Non-B through the e-visa site when I was still in Canada, after a few weeks without a response, I left for Thailand and entered on a visa exempt stamp. If the e-visa gets approved while I am in Thailand, can I still use it by doing a border bounce (or fly out/in)? I already reached out to the embassy and consulate in Canada with no response.
TLDR : Answer Summary
Yes, you can use your approved Non-B e-Visa while in Thailand. After it gets approved, you print the PDF confirmation received via email, which serves as your visa instead of a sticker. To activate it, you must exit and re-enter Thailand (a border bounce) and present the printed PDF at the immigration checkpoint. Remember, the e-Visa is valid for entry for three months from its issuance date.