The LG Nexus 5X was one of the best yet affordable Nexus smartphone back then, though not having great performance internals like the Nexus 6P, it had a Snapdragon 808 system-on-chip along with 2GB of RAM, which isn't too bad that point of time. If you are still holding on to one, there's actually a good chance that your Nexus 5X could breathe new life by upgrading its processor and RAM, as XDA-Developers user Cathair2906 has encountered a bootloop issue on his Nexus 5X, he sent it over to a repair shop in China and paid RMB400 (RM255), which in return gives him an upgraded Nexus 5X with a Snapdragon 810 processor and 4GB of RAM, yet he was also able to update to the latest build of Android 7.1.2 with the latest April security patch.
One will simply question how this can be achieved, as most phones have their components soldered on to the PCB, the Nexus 5X uses a PoP (package on package) packaging technique, which the SoC has its RAM sitting on top of a pad, since fixing the bootloops require replacing that block, it makes sense to upgrade the SoC and RAM together. This job is apparently done by an unofficial repair shop in China, which also services other smartphones as well, and knowing where most smartphones are being assembled, it isn't surprising if the repair center had the parts needed for the job.
If you don't mind making a trip to China for a better Nexus 5X, the service center is located in Shenzhen with the following Chinese address: 深圳市福田区华强北远望数码城一楼1065, if you prefer you could also add the person's WeChat ID at HUijhuang, you may also need to know how to converse in Chinese as well.