<script type="application/json" id="chart-data">{{ charts.chart_data|tojson|safe }}</script>
in your extension template could work. But please do note that this might break, I consider the charts an internal implementation detail and want to keep the freedom to modify how they work.
2019-06-26 * "EE Top Up"
Assets:GB:Coinbase:ETH -0.04020595 ETH {{10.00 GBP}}
Expenses:Communications:Mobile 10.00 GBP
PotterScholar
;ethereum purchases
2017-07-14 * "Coinbase" "Crypto: Ethereum Purchase"
Assets:Cryptocurrency:Ethereum 0.51772979 ETH {193.15 USD}
Expenses:Fees 2.99 USD
Assets:Checking
;ethereum sales
2017-12-07 ! "<person>" "Crypto: Ethereum Sale"
Assets:Cryptocurrency:Ethereum -2.55155802 ETH {} @ 427.10 USD
Expenses:Fees 16.24 USD
Assets:Checking 1089.77 USD
Income:Other:Investment-Income
PotterScholar
The gains/losses are in Income:Other:Investment-Income, the basis is maintained in Assets:Crypto:Eth, and the gross profits are in the cash account