Always, the talk is of miles. I had an associate who was a keen racer, late 50's 20 years ago. "Get the miles in!" was his mantra. I never done that; I've always rode alone, sometimes encounter someone on the road for a natter. I always went out for an hour, two hours or 45 minutes over my favourite hilly course with 1 in 4s to contend with.
I preferred those and still do. With the state of the roads, the Gym seeemed the sensible option with the bike courses they run (I've mentioned them before) which also took on the task of motivating me.
Since it was shut it was back around the local roads again, over the hills.

It is harder. In the Gym you subconsciously work out your best power delivery options for what comes next. Your feet dance to the music, and recovery is short so you cheat on the loading. On the road, you tend not to. there's always the top of the hill; the harder you go, the faster it comes and you get out of breath in a way that just doesn't happen in the Gym.
I've enjoyed the fresh air, my roadbike, even the traffic; the enthusiasm's still there but for the bumps. I'm too old to do bumps in the road without a bit of cushioning, particularly the wrists in my case.