In the end I found a way to export the sms text messages managed by Signal in plain-text, and I found a Signal fork that does just that!!!
(GitHub - johanw666/Signal-Android: Fork from a private messenger for Android with extra options added: full backup and (partial, ony text) xml backup of messages. Restore can happen at any time, not only after a fresh install. Import SMS database. Removed apk expire. Choose between passphrase protection and the Android screenlock. More conversation colors and themes. Choice for the backup location (internal or removable storage). Set the maptype in the place picker. Option to treat view-once media as normal media. Option to ignore remote deletion. Choose between FCM or websocket notification delivery.)