Let me make explicit a key requirement that apparently is not as obvious as I thought: the improvement we look for must not change the current UI in any way. Remember that we have tutorials, papers, instructions all over the place with the current UI, and many active users of the current UI, including journals that have trained their vendors about it, and are quite happy: it is too late (and counterproductive) to make changes now. Please do not debate this point: it is a firm decision.

After recent exchanges with @hboutemy and Charles Sabourdin, here is a clarification of the scope of this task.
We need a Maven repository lister that addresses the following issues:

Let's organise a call next week to explore the options, including the new opportunities of testing that emerged recently.

Did you consider PMem (and other configurations for Intel Optane memory) in your discussion? It offers a very interesting price/performance ratio.
There are machines on Grid5000 available to test this technology if needed.

@hboutemy : I wonder if you are aware that we have now in place a grant program that allows to fund development of listers like this one.
All the information is available at https://www.softwareheritage.org/grants and you can mail me for more info if needed.

Work is in progress with the first academic ambassador.

We would like to see this in prod as soon as reasonably possible.

Thanks for looking into this!