Can I connect a Suunto or a COROS?

Not directly, and not yet. Both are on the Coming soon list at the bottom of Settings > Your data, without a date, and neither is in the list of sources you can connect. Their data can reach Trailwise another way today: both watches sync to Strava and to Intervals.icu, and Trailwise reads both. You can also export a single session as a FIT, GPX or TCX file and upload it through Manual import.