I’m in Amsterdam, yeah - good one with doing the intervals against the wind (it’s as much mountains as we get around here, with the downside that there’s no mountain top).
I appreciate your challenge, it’s a good thought to be going outside in terms of specificity! as you say, indoors for sure is way more time-efficient, and it made much of my tri training possible given other obligations (it takes me >20min to get out and back from the city plus kitting up, washing the bike). another big downside to outside is - even with good roads and segments, still - road traffic/running out of road/stoplights. and overall safety at high speeds on open roads.
another huge plus to outside is that you go places and experience nature!
all in all, I was actually surprised by how close I came to the actual session goals in terms of NP.