Author here – you can also browse the single-file source code to dump the messages, which contains the poorest protobuf and tar implementations: https://github.com/bitonic/wadump/blob/master/dump-messages.js :)
On iOS you can simply make an encrypted backup on your computer, decrypt it with iOSbackup and get the sqlite database and other data WhatsApp uses on the phone. It is fast, complete and convenient.
I haven‘t checked if this approach is also possible on Android.
Sadly as far as I know that isn’t possible on Android. I actually used the method you mentioned, plus https://www.wazzapmigrator.com/ , to get my messages from iOS to Android.