Vertical speed isn't displayed anywhere in Garmin Connect. You can work it out from the elevation chart (over time not over distance) if you want to, it's kind of a pain, or with splits.

All of the data fields on Connect are for the entire activity, so unless you only recorded the way up on a climbing ride, it wouldn't be terribly useful. Arguably it would skew your number to be meaningless. But if you mark your climbs as laps, the splits tab gives you moving time and elevation gain per lap. How feasible that is depends on how your ride is set up; lots of small climbs would be a pain in the ass, a few bigger ones are easier. Maybe you can pick a hill or two to record your VAM on?

Here are two examples of using lap/splits to get vertical speed in Garmin Connect:

https://connect.garmin.com/modern/activity/914030386
https://connect.garmin.com/modern/activity/913079039

I don't use Strava so I can't help you there.