Is there a ONU/router that support LEDE/OpenWRT firmware and fiber optical (SC Simplex) ?
Your best option would probably be a router with SFP ports (e.g. mvebu) and a sfp based transceiver matching your ISP's requirements (don't expect finding one to be easy or your ISP to be overly forthcoming).
If an SFP solution works, you might be able to do it with an SFP enabled smart switch and any router of your choice. This will give you a lot more flexibility in choice of router.
With ATT for example, this just won't work, they use 802.1x certificate based authentication and they won't give you the certificate.
The Ubuquiti Edgerouter X SFP:
In cases with fiber optic ISP can configure my router(ONU) remotely. In case with openWRT firmware , they can do this or not ?
No. thankfully
Thanks for answer. I just knew that they can upload their configuration file using OLT to any ONU and wanted to be sure