Unless you are using a device that is Wifi 6(ax), then you aren't going to get wifi speed near a gig. I get about 400 with a laptop that's wifi 5(ac)
Yes can get any extender you want be you will need to wire it with ethernet. If you get the Verizon one you can utilize the coax in your house.
Also keep in mind a gigabit connection is way overkill for most applications. The gig speed is for bandwidth sharing between multiple users. Not really about one device getting a gig. For example, you only need 25 mbps to stream 4k.