I'd like to send thankyou letters to soft credit contributors, but I don't find a token for soft credit amount. Not even in CiviToken extension. Is it possible?
You can use my Soft Credit Tokens extension for this. Note that the README points out it only pulls the data for the most recent soft credit on the contact, which may not be the correct one. This was due to a limitation that existed until Civi 5.43 - this can be fixed now, but I'm not really using the extension anymore so someone else will have to do it.