Luckily the Bubble export has improved to the point that it is now useable. The csv export queues up in the background and sends you a link. Those files are then easily imported into your database using your favorite db tool…I suggest doing the import outside of wappler, rather than building something to perform the import.
The Bubble data api is limited in a number of ways, but can definitely be accessed from api actions in wappler – a good use case is to perform a bulk export/import using csv, and then get recent changes via the api if they are few in numbers.