You're now the second guy who says a 12 months bank statement print--out from Bangkok Banks app was accepted at CW immigration.I told that here just a couple of days ago,and they said "no way at CW", so I'm glad, you are now basically the proof it does work. I just hope those who didn't believe me reads this.
Wise would be my answer,but if you want the transfer to show up as international without a doubt,then a swift bank to bank transfer is the best choice. For future transfers, go for Wise.
I have opened bank accounts on tourist visas in 3 provinces, plus some more while living in Thailand.10 years ago you could easily open a bank account almost anywhere without breaking a sweat.
There must be some agents on Koh Samui in for example Chaweng or Nathon. Hop on your bike and ask them in person. The tricky bit will be legalization and translation.