Here is my 2cents on the drive upgrades.

I have tested the Visiontek 2tb it runs hot, it seems to keep on ticking for now but its still running too hot. With a simple copper plate heat sink it has no effect other than slowing down its initial temperature peak by a few seconds. A long 70mm heatsink seems to help but only do this if you are aware it could short against something when done in the stock location.

The KingSpec 2tb XG7000 is double sided, DO NOT use a double sided drive in this, the Go was engineered to NEED a single sited drive, you can force it, but you will be risking damaging your wifi, BT, NVME and NVME slot. While Lenovo has said upgrading the NVME wont void the warranty, forcing a non fitting part in is not a great plan. Just Don't. Single sided drives only.

For 2230 drives with adapters, dont use the ones with the metal inserts unless you make sure to put some mylar or kapton on the bottom of them to keep them from shorting against the board. There are plans online for printable adapters, remember these drives can hit 100c, PLA will not hold up well, check the 3d_printing chat for suggestions on that.

For 2280 support, There are basically 3 kinds of adapters in use.
The original one has 2 boards and a white ribbon cable, This is the only one I have never touched.

The second one looked at was ones made by ADT-Link, I did purchase an ADT-Link R44MF 5cm version, this version has the following issues;
It's too long, the metal boss to screw the 2280 down is past the end of the battery so it will never fit in the case.
It is also using very heavy cable that is hard to bend.
If you leave the stock battery tray in but remove the Graphite tape, you might be able to almost get this to fit correctly. You will literally have to bend the cable coming off the part that plugs into the NVME slot 90deg straight up and then in 2mm 90deg left to extend over the battery. Tight bends like that lead to breakage, and even bent right you will have to deal with a great deal more BT issues like I had while using this board and the back cover will not fit unmodified. Check the 3d_printing channel for options.https://www.amazon.com/gp/product/B0BZVJFLHC/

The third and newest has a very short copper colored ribbon cable and is primarily distributed through aliexpress. This one is the one I am betting most will use. The cable is light, located in a better position for this device and was built to fit. If you cut back the graphite tape on the battery cover under this adapters 2280 connector it almost fits perfect in the stock cover with no real option for added cooling. It will fit under some of the 3d_printing channels designs fine.
https://www.aliexpress.us/item/3256806121913033.html

I have posted a LOT in the modification_channel some in the legion_go_accessories and the legion_go_general so search for images and things that interest you or ask me in the public chats, so I may not have to answer the same question 100 times in private.

But as someone who has tested 3 2242 drives, 1 2230, and 1 2280 here is my suggestion.

If you can, do not install a larger NVME. If you must, weigh your options carefully considering whats above. Lenovo has said "swapping the SSD out does not void warranty so long as you don't damage any other parts in the process" so, the ADT-Link I do not recommend myself. If you absolutely must do an internal upgrade consider not getting a PCIe4 and instead get a PCIe 3 drive. It will be slower and less likely to get very hot. Also when peeling back the graphite sticker and removing the old drive, I dont recommend sticking it to the motherboard under where the original drive sat. I kept it on top of my 2242 Visiontek but when I tried the 2280 adapters I cut the end off.

If you are more concerned with space and not so much speed there are external alternatives that can provide quite good performance. Check https://discord.com/channels/1141568886450442395/1146141861602394112/1189077108216049744 for an example.

Here is my point, the bottom line. For me the Legion Go is a gaming machine. If I were to have a drive die, I get it replaced, and rebuild. People who are looking to multipurpose the Go, you should consider how important what data you plan to store is.

Who am I, and what is my stake in this? Been an IT professional and electronics hobbyist since I modded my first computer in 1981. I bought out of pocket all the drives and adapters and stacks of heatsinks to test. I am enthusiast, I get nothing out of doing this but trying to save others from having to go to the same expense. AMA I ma rahlquist on the Legion Go discord. Or ignore everything I say, it is free advice on the internet after all LOL.

Peace Out.