@FredJ the problem with Suunto hrTSS is that it evaluates time in zones not the actual HR rate. And unfortunately in Suunto zone 1 begins at zero. Even making your resting heart rate higher won’t change this.
I made a test recording my HR just sitting at the table and got similar result as when I jogged lightly in zone 1 for the same amount of time.
Solution would be to have lower limit on zone 1 like Garmin has.
Until then, I use rTSS (pace) for my walks, which is roughly 33% of hrTSS, and 66% hrTSS for my hikes, provided the terrain is hilly. The more flat is the terrain, the more I lean towards the walking percentage