Not hard. Strfry provides some nice migration tooling actually. Coming from nostr-rs-relay I was able to run:

sqlite3 ./nostr.db '.mode json' '.once out.json' ' select content from event;'

cat out.json | jq --raw-output 'map(.content)| .[]' >> out.jsonl

cat out.jsonl | ./strfry import

It imported the ~700k in just a couple minutes. Worked great.