Still there are a huge data in L0 and as you know that there is not possible to convert this level to L1 SLC images, So it is not possible to add a module via SNAP to convert this L0 to L1, I think this topic has been raised by other colleagues, but I’d like to renew the demand,
Once a public-domain SAR-processor is available, we will support it with SNAP. There are some rumors that such a processor will be released in not-too-distant future. It should be noted that with such a processor the processing to L1 is ad hoc and will not produce SLC:s identical to those produced by the PDGS.
I have an idea if it possible to discuss it with your colleagues in The Payload Data Ground Segment (PDGS), It is possible to add an online processor within S1tbx? to convert L0 to L1 identical to SLC we get now from any website provides Sentinel-1, in this case I think will mitigate the load that they have for huge data conversion.