Unfortunately ETRADE for example does not make exporting all transaction easy. Last time I looked at their API it involved manually authing via a http flow signing into your ETRADE account to get a temporary token that expires. Not exactly a flow that can be used for long polling account activity.

I haven't researched much on Robinhood or Coinbase but I suspect they have much better APIs. That's an idea where a plugin system would be awesome, something like Plaid but for brokerages and Crypto exchanges only.