After researching, tracing and trying multiple config changes finally got my Sonos S1 working with TrueNAS-13.0-U6.2. Here my configuration, hope it will helps others:

Services / SMB:

Enable SMB1 support: checked

NTLMv1 Auth: checked

Guest account: nobody

Auxiliary parameters: unix extensions = No

Sharing / SMB:

Name: Music

Path: </your/path/to/music>

Purpose: No presets

Enabled: checked

Enable ACL: checked

Export Read Only: checked

Browsable to Network Clients: checked

Allow Guest Access: checked

All other checkboxes: unchecked

Auxiliary Parameters: public=Yes

Sharing / SMB / Share ACL:

Share Name: Music

SID: S-1-1-0

Domain:

Name: Everyone

Permission: FULL

Type: ALLOWED

Then on you Sonos S1 phone app, go to Settings and "Music Library Setup" and add:

//<IP_OF_YOUR_NAS>/Music

(leave user/passowrd blank)