Hi Punkinann,
Yikes, that's a lot going on with your phone!
Those problems you are seeing do not appear to have anything in common other than the fact that they're all connected to the motherboard. Combined with a diagnosis of a failing WiFi chip, the first thing that comes to mind is significant issues with the logic board.
That being said, it's also possible these are separate problems. There are two of your issues that could conceivably be related; the bluetooth and WiFi reception issues. There are antennas for both of those, combined into a single flex assembly that could conceivably be at fault.
iPhone X Wi-Fi/Bluetooth Antenna - iFixit Store
I wrote the guide to replacing that part; here's a link to it.
iPhone X WiFi Antenna Replacement - iFixit Repair Guide
There is another little piece of cabling that's labelled as a Bluetooth antenna that you might want to consider replacing at the same time.
iPhone X Bluetooth Antenna - iFixit Store
There's a separate guide to that as well, but the steps are basically the same so it'll be easy to replace when you do the WiFi/Bluetooth antenna replacement.
iPhone X Bluetooth Antenna Replacement - iFixit Repair Guide
The touch screen issue is puzzling. Normally you'll see a defective digitizer consistently fail; they don't usually come back after a reset, so I'm not sure what to suggest here. I'd probably start with opening up the phone and checking the digitizer connector; that's the one the spudger is pointing to in this picture.
You'll want to unplug it and take a magnifying glass and a bright light and check the connectors on both the motherboard and the cable for any bent, broken or missing pins. Also check the entire cable for any tears or crimps. If you find any damage on the cable or the cable's connector, the only solution is to replace the entire screen. Clean both connectors with isopropyl alcohol (90% or higher; don't use the 70% stuff we all have around the house) and see if that makes any difference.
The earpiece speaker is part of the front sensor assembly mounted on the display. Replacing the entire assembly will result in the loss of your Face ID function, as parts of that assembly are paired specifically to your motherboard and can only be replaced by Apple. However, if you can do a very small amount of soldering (or know someone who can), it is actually fairly easy to replace just the speaker by itself without losing Face ID. I got the idea from a guy on the internet who figured it out and wrote a guide for it.
iPhone X Earpiece Speaker Replacement Without Losing Face ID - iFixit Repair Guide
You can find the earpiece speaker for sale all over the place; Amazon, eBay and AliExpress all carry it without the rest of the assembly. Here's the one iFixit sells.
iPhone X Earpiece Speaker - iFixit Store
That part is fairly straight-forward to replace. Here's the part and the guide.
iPhone X Loudspeaker - iFixit Store
iPhone X Lower Speaker Replacement - iFixit Repair Guide
I've done a lot of work in iPhone X's and if it was my phone I'd replace those four parts (both speakers and both antennas), check and clean the digitizer connector and see where I was. If the WiFi issue persists, there are repair shops that can swap out your WiFi chip; @hellomacos, can you confirm and/or offer any suggestions? (He's our go-to guy for microsoldering.)
Hopefully that'll give you something (okay, a lot actually) to think about. Feel free to ask questions! Hope it helps.
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