I'd call my general experience a success.
First, the staff at my hotel were very helpful, both in unloading the parts of my scooter and carrying them up the front steps for reassembly; providing parking out of the way in the lobby.
A few of them asked if they could ride it, and I let the concierge I've gotten to know in the past move it across the lobby for me.
Later I was given permission to come and go through the hotel courtyard and the ramped service entrance.
I first took it out last night, with my fiancée walking alongside me, from the Opera House area to a sushi restaurant in Japan Town, normally about a 7 minute walk.
The restaurant parked my scooter in the spot closest to the front door so I only needed to walk with my cane to the inside elevator and our room on the third floor (where we were met by my attorney, her mother and her fiancé whom I'd previously met in her home about 2 years ago).
Getting back to the hotel through Japan Town was uneventful, using sidewalks about 90 percent of the time and hugging the curb when I needed to be in the street.
Today was a much more challenging trip:
Starting at the Opera House area we traveled to the US Consulate, about 1km away.
There are many areas where the sidewalks are blocked by food vendors, construction and parked motorbikes, so I was out in the street, as close to the curb as possible, for about 40 percent of the time.
No real problems sharing the far right lane with motorbike traffic.
I did reach a corner where the sidewalk didn't have a handicapped ramp to the street (ironically, catty-corner from the US Consulate; beacon of Americans with Disabilities Act rights).
I just needed to dismount and slowly maneuver the scooter down from the sidewalk to the crosswalk below.
Once I discovered the correct approach where I could get my scooter past the sidewalk barriers, I made it into the American Citizen Services (ACS) entrance where they inspected and stored the scooter and transferred me to a manual wheelchair pushed by my fiancée.
I offered to walk inside the compound with my cane, but they insisted we use the wheelchair.
When I'd finished having them notarize 3 documents for me, we left and continued on to the
Trung Tâm Dịch Vụ Đối Ngoại (Foreign Service Center) Google Maps link about 800 meters away, where the Vietnamese government basically notarizes all of the US Consulate's notarizations, thus making them acceptable for use within Việt Nam, including translations, if requested.
When we finished there, we headed back to our hotel next to the Opera House (about 900 meters away).
The main problems we encountered (at city park Công viên 30/4 and later at Vincom Plaza) were the motorbike barricades that so completely shut out motorbike traffic that it's impossible for any kind of wheelchair to pass.
So from the Consulate to the Foreign Services building and back to our hotel, I was probably in the street over 50 percent of the time.
I think it was very helpful that I'd already spent a lot of time walking around D1 in the past.
I felt as if I had just as much right to use the street as a woman with a flower cart or a motorbike driver would.
So while I wouldn't recommend a similar endeavor by a short-term tourist unfamiliar with the streets of Việt Nam, or someone unable to get out of their wheelchair and do the things I've mentioned, I'm sure a person living in Việt Nam, in circumstances similar to mine, could successfully use a mobility scooter in and around their own neighborhood.