I’ve been finding it difficult to track my progress while swimming with a swimming cord. Is there a swim watch or tracker that can provide an estimate of the distance covered while training like this?
I've not used it, but the FINIS Swimsense watch claims to count strokes (and laps and distance and...) which then can be uploaded to a computer. There are also on-finger counters, although those might be more applicable to lab counting and not your application unless you really like twitching your fingers...
Timed swimming on the cord, compared with known times for measured distances free swimming, might get you an estimate.
Personally, I find that swimming on a cord has a very different effort-to-stroke ratio than regular lap swims - it is more like using paddles in terms of what my shoulders feel.