DHCP limit/DHCP lease

For FTTH/GPON , do you get to keep the same IP address if your CPE stays online? aka DHCP renewals getting the same IP.

If you connect the ONT to a switch, can multiple devices each get a public IP? I guess the ISP may be limiting DHCP to 1 IP per port, but I have used ISPs that didn't configure anything to prevent users from receiving more than 1 public IP behind the ONT