My expectation when setting up my structs is that I would be able to control the Salesforce api name by using a soql, json, or other tag. I don't want my Go structs to have field names like ExternalId__c. It wasn't until I dove into the code and saw extensive use of mapstructure that I realized everything was based on the field name.
https://github.com/k-capehart/go-salesforce/blob/main/dml.go#L178-L183

Today, I could use mapstructure:ExternalId__c as a tag and I would be able to name my struct fields however I want, but that unnecessarily ties the salesforce api to the mapstructure package.
https://pkg.go.dev/github.com/go-viper/mapstructure/v2#hdr-Field_Tags

The decoder config allows you to set your own tag name, so I would propose something like salesforce:"fieldName", e.g.
https://pkg.go.dev/github.com/go-viper/mapstructure/v2#DecoderConfig

type account struct {
	ExternalID string `salesforce:"ExternalId__c"`
	Name       string
}

This is more obvious what the expected behavior is, and doesn't tie the implementation to mapstructure in the future. I thought about soql, but that has too much baggage for other use cases, and mapstructure wouldn't be able to parse it properly. There's a case too for json, but that is probably too overloaded.