If you want to cut out your ISP device entirely, you will need to know exactly what setup your ISP has given to you, and then match that with your own hardware. The https://pon.wiki/ and servethehome forums are a great place to start for this.

If your ISP device has a passthrough mode that you are happy with using, practically any device with two gigabit ports will work for a 1gbps internet connection. I use a https://friendlyelec.com/ device, because they come with friendlywrt preinstalled, but your choice of router software is basically entirely preference based.