In terms of Workout Levels, outside workouts won’t get the same detailed workout scores you get indoors. There are just too many variables, so your completed outside workout will receive the level the workout had planned for you. In other words, if you do a Sweet Spot 5.0 outside, you’ll receive a level 5 for it.
However, this is just the visual Workout Level, and isn’t taken into account by the AI. Exactly as with indoor riding, the AI looks at the totality and details of what you did—time at power, recovery, etc. If you do half of what you had planned, the AI will adapt accordingly. The same is true if you go above target or add extra intervals—the AI sees this and responds.
Perfection is impossible outside. Don’t stress over the occasional stop sign, coast down a hill, or other normal variables. However, it’s definitely a good idea to choose a route that suits your workout. If you have 20 minute intervals scheduled and encounter long stoplights every 3 minutes, that’s going to impact the quality of your workout and the AI will recognize this. This isn’t the AI penalizing you gratuitiously; it’s a reflection that you aren’t getting the stimulus the workout was designed to acheive.
I think a good way to think of this both indoors and outside is that the AI is never trying to catch you doing something “wrong”. It’s just looking at what you do, assessing its physiological impact on you, and deciding what that means going forward your calendar. Outside riding is more variable than inside, and that’s not necessarily a bad or good thing—it’s just how it is.