TIL you can stop a resliver (by detaching the target device), move it (or in my case, rename it) and run a zpool replace again and the resliver will pick right back up where it left off.

So story time. I damaged a disk by being stupid and trying to get serial numbers off of hard drives on a running system. I put in a replacement and let it resliver for two days before realizing it was a smarter idea to reference the drive by its gptid rather than its block device because block device assignments are subject to change.

So, all I did was detach the disk and replace it again by its gptid and the resliver just happily picked up right where it left off!