Hi Aspen,
It sounds like you've done everything reasonable there is to be done without opening up the phone. Only other thing I can think of is to get a magnifying glass and a bright light and look inside the charging port. Check for any bent or broken pins (yes, they're hard to see) and any dirt, lint, dust or corrosion inside there.
If that comes up empty, then I'm thinking it may be time to replace your charging port. It's kind of on the high end of the medium difficulty range, as you have to pull the motherboard to get to it, but if you follow the guide it's very doable. I've had my 2XL open and it's not a bad job really; certainly no harder than most phones.
Here's the part you need.
[link|https://www.amazon.com/UPONEW-Charger-Connector-Charging-ReplacementMic/dp/B07PPRH1BH|Amazon.com: UPONEW for Google Pixel 2XL G011C USB Charger Connector Charging Board Port Dock Flex Cable ReplacementMic Part Flex Cable for Google Pixel 2 XL 2 Plus G011C 6.0" : Cell Phones & Accessories|new_window=true]
Don't forget the replacement adhesive to put the rear cover back on.
[link|https://www.amazon.com/PHONSUN-Pre-cut-Frame-Adhesive-Google/dp/B07F6D3ZTZ|Amazon.com: PHONSUN Pre-Cut Frame Adhesive for Google Pixel 2 XL Pack of 2 : Cell Phones & Accessories|new_window=true]
And the instructions on how to do it.
[guide|108463|Google Pixel 2 XL Charging Assembly Replacement - iFixit Repair Guide|new_window=true]