We had grating for the
cockpit sole. When the varnish came off, we left it bare. The unfinished
teak was not slippery. If the rain grows moss in it, soak it with buckets of
salt water, which will kill the moss. We had
teak covers on the cockpit lockers of the previous
boat, and left the rims varnished. You had to be careful to step where the varnish wasn't, but those were essentially smooth surfaces. I have seen varnish where the people have sprinkled glass beads on it for non-skid.
If you're really looking for non-skid, consider something like acrylmeric sportcote. We've used it for years now, and it holds up well. You
paint it on.
Water clean up. Sorry, don't know where to source it in
Canada.
Ann