We have the possibility to add an offset before MAC address on LS1028a ENETC?
Layer 2 offset. The number of octet pairs from the start of the frame that the parser should expect to see
before the first byte of the Ethernet DA.
If you expect that the parser to be able to interpret the frame as Ethernet and continue parsing, the answer is that ENETC will stop the parsing process depending on the value that will be found at eth_type position. The parser is not able to parse a custom header that is added in front of the DMAC. You will receive the frame but its type will not be reflected in the parser summary.
To conclude, parser is not able to go further than L2. It's up to the software layer you have, to decode the received frame