Powerline extenders can work okay, but they tend to be hit or miss. In the best scenarios I've seen maybe 10-20% of the advertised link speed (so like 100-200mbit), but for some reason in certain settings I've just had them drop out repeatedly (especially when certain appliances come on), or fail to be able to work across certain junction boxes or powerstrips too.
It's worth a shot, but honestly in a lot of sites even without line of sight, I've found a wifi based meshing solution or P2P solution to deliver better bandwidth.
I've joked that powerline extenders should just cheat and carry a dual wifi radio backhaul with internal antennas....
But in all seriousness, reliability is the big question. I've had cases where the connection quality is highly variable and it was frustrating finding any sort of pattern or explanation as to why. I've more or less sworn off the technology and I'd rather add more intermediate wifi backhaul hops to deal with this problem.