Can I use I2C protocol for product with SPI interface ICs?
I would suggest something like this instead if you can change your design slightly: https://www.nxp.com/docs/en/data-sheet/SC18IS602B.pdf

This is an I2C-SPI bridge. It responds to I2C transactions to a particular address and will perform SPI transactions in response. You would hang this off your I2C bus and have it be the master of your SPI bus. It has 4 slave-select outputs.

For going the other way around (hanging all the I2C devices off an SPI interface) there's this one: https://www.nxp.com/docs/en/data-sheet/SC18IS600.pdf

It is an SPI-I2C bridge. I think if you're doing an FPGA this would actually be the easier one to do, since then you don't need to worry about open-drain (especially combined with the necessary clock stretching logic) with the FPGA. Generally SPI interfaces are easier to properly implement on FPGAs.