There doesn't seem to be a large tangible response from the G7 as of yet, excluding the statement you mention in your question. One example of a collaborative effort, however, is the search for an accurate test for coronavirus antibodies which is suitable for home use.
The UK Health Secretary, Matt Hancock, mentioned this in his press conference on Friday, April 3rd, saying in response to a question about the UK's testing strategy:
We have provisionally ordered 17 and a half million, not three and a
half million antibody tests. But, as I’ve been absolutely clear all
along, we’ll only use them if they work. And, in fact, on the G7 call
earlier, it’s clear that no G7 country has yet found a home antibody
test, which is pillar three of the testing strategy, that works. But
we continue to search for one. Again, this is an area where the
science is constantly developing. And there’s a huge amount of global
effort going into finding one of these tests that does work.
The full transcript for that conference can be found here. He also mentions that on that day he "spoke to [his] counterparts in G7 to coordinate our research efforts over this and other things". This seems to imply that while we are not yet necessarily seeing grand joint funding initiatives or physical supplies being delivered as a joint response, there are efforts being undertaken behind the scenes in order to coordinate the G7's strategy.
It should be noted as well, that there have been other joint statements by the G7. Notably, there have been two statements from the G7 Finance Ministers and Central Bank Governors.
The first, on March 3rd, served to welcome efforts by the IMF and the World Bank among other institutions to help countries respond to the crisis, and to affirm that they stand ready to provide further help. The second, published on March 24th, was rather more meaty, and provided details of the collaborative work being undertaken in order to provide funding for the response to the crisis, including measures such as liquidity support, fiscal expansion, guarantees, subsidized loans, tax deferrals, and loan repayment deferrals. They also signal their support for providing emergency financing in the future, as well as "[standing] ready to contribute further resources to multilateral efforts aimed at helping the most vulnerable and least developed countries", suggesting that we may see the G7 assisting with debt forgiveness for LEDCs, as, for example, African finance ministers have called for.
Notably, the statement includes a commitment to do "whatever is necessary to restore confidence and economic growth and to protect jobs, businesses, and the resilience of the financial system". This is highly reminiscent of the famous Draghi "whatever it takes" speech, which was given in the middle of the Eurozone debt crisis in 2012. It also notes that "Consistent with the direction from the G7 Leaders, finance ministries will coordinate on a weekly basis on the implementation of these measures and take further timely and effective actions."
It seems therefore that although we might not yet be seeing the sort of large-scale direct action that your question asks about, there are significant collaborative efforts being undertaken behind the scenes which are both informing countries' efforts at coping with the crisis, as well as ensuring the stability of the financial system and its ability to aid the fight against the pandemic.