Yes, I would suggest refind. See this link.
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https://teejeetech.com/2020/09/05/li...t-with-refind/
There is a ton of documentation on Refind. The ultimate doc is here -->
https://www.rodsbooks.com/refind/
I have a triple boot setup on 3 disks, one being an nvme drive. I gave up on windoze a long time ago, so it my setup is all Slackware. I don't think that should be an issue though, since you have W10 already on your nvme drive, an will have a efi partition. You will be adding things to it for your Slackware setup. You need only one efi partition.
Best of luck.