First of all, please respect that this specific thread is a feature request discussion and meant for support so please start a separate thread if asking for support/help and not discussing the feature request.
Understand that for support will need Zigbee Coordinator chip and firmware have today to migrate from.
As franscisp mentioned above; “znp_backup” (backup via zigpy-znp) is only for Texas Instruments Z-Stack / ZNP adapters/firmware, and “ezsp_backup” (backup via bellows) is for only Silicon Labs EZSP (Silabs EmberZNet Serial Protocol) adapters/firmware. There is as of yet no backup support for other types of Zigbee Coordinator like “deconz” (ConBee/RaspBee), “zigate” (ZiGate), or “xbee” (Digi XBee).
Both “znp_backup” and “ezsp_backup” save/restore using “Open ZigBee Coordinator Backup Format” which indeed means that you can backup a Silabs EZSP adapter and restore to TI ZNP or vice versa in order to use it as a migration method.
The same Open ZigBee Coordinator Backup Format can obviously be used for migrating from older to newer adapter hardware/firmware with old respectively new chips from same chip manufacturer. Read: