I would like to be able to track the total time I have spent on each of the various activities I track (cycling, etc.) over time (week, month ...) to see how I have progressed (or not). is that possible?
You can't do this for multiple activities at the same time, but you can do this for one activity at a time in the Connect website:
1) Open: https://connect.garmin.com/modern/progress-summary
2) Select the time period

3) Select the sport (or subsport)

If you're looking for a site that can give you a weekly or monthly breakdown, you can use https://www.runalyze.com, which is free and syncs with your Garmin account.
Note that Garmin will only allow up to 5 years of activities to be synced via the API, so you will have to do some additional manual steps if you want to import more data into runalyze. (Basically you will have to request *all* your data from Garmin and manually bulk import your activities into runalyze)

