DLDI (Dynamically Linked Device Interface) files for Nintendo DS homebrew files that allow them to fully communicate with the flash cart device they are running on.
These are generally no longer needed as flash cart manufacturers commonly incorporate automatic DLDI patching in to the system firmware/loader.
I may try the new ram site, and download more RAM to my Switch. Not sure if ddr3 is the right ram
for it tho. Edit- no it uses floppy Ram, just like @AncientBoi