Assuming you're okay at the SSH console and can read internet HOWTO posts on uncompressing a tar file (the backup). You can take a backup on LE 9.2.6 (using the settings add-on) and make a manual/selective restore of the following from the backup:
/storage/.kodi/userdata/sources.xml
/storage/.kodi/userdata/addon_data
/storage/.kodi/userdata/Databases
/storage/.kodi/userdata/Thumbnails
The Python 2>3 changes (and arch change) mean you need to reinstall add-ons anyway .. consider it an opportunity for spring cleaning. The scrapers are also different in Matrix so you can either take the highest numbered DB files and existing Thumbs cache and use it again or only copy sources.xml and then rescrape. The guisettings.xml file has other config, but some will be x86 specific so it's always 50/50 how that turns out when swapping arches. With practice it takes 5 mins to reconfig everything in Kodi settings so it's not a big deal.