That’s part of the issue none of my sinks have nozzle attachments that screw off they are one single attachment and the one has the hose attached to it so no adapters are made for them.I love my spectrapure one with their nice expensive filters. I change pre filters every 6 months, got 6 years out of my last membrane and 2 years out of their max DI.
I question whether these cheaper units that don't seem to have standard filters really save money over time. I kind of doubt it.
FYI for sink hookups... I went to ace hardware with the part that screws off the sink (the little mesh end) and they were able to get something to work. It took a few different parts screwed together.
I ended up eventually putting a removable T to the cold water line though.