TLDR: Easy to do a quick visit using grab app for pickup/dropoff; felt safe the whole time; spent about an hour by the lake.
Had a Grab taxi drop me off (and later pick me up) at a Pho restaurant on the main street (83 Đ. Hoàng Hoa Thám, Ngọc Hồ, Ba Đình, Hà Nội, Vietnam) then walked down a short lane to reach the wreckage in the lake.
Visited on a quiet Monday morning around 8am as the city was just waking up. Grabbed an egg and cheese crepe from a vendor outside the hospital (next to the lake). Spent about an hour walking around the lake, taking photos, watching locals gather their groceries from the morning market by the lake. This was one of the more emotionally stirring spots on my trip to Vietnam...