Hi Dhiren,
the idea about bash auto completion sounds interesting to me and I would like to work on it
Awesome! You are in :)
Do you recommend to first play more with flashrom and then work on this feature?
Yes, I recommend to do few small things first. For example, this is one more easy project that we created just recently: https://ticket.coreboot.org/issues/416 (in addition to https://ticket.coreboot.org/issues/405 that I mentioned previously). If you want you can create an account on bug tracker and then you'll be able to assign ticket(s) to yourself!
The reason is that auto completion is meant to cover most often used commands. Ideally you would use flashrom by yourself for some time, and then you will have a much better idea what are most often used commands.
Good luck!