A completely different view---Most people new to riding bikes want to be very upright. This puts all the weight on your Behind. If you are leaned forward some it puts some weight on your hands and it puts most of your bodyweight behind the pedals where you are pushing off.

Many people ride with the seat too low also putting more weight on the seat and making your legs much weaker. Bar ends on the handlebars will pull your weight forward and stretch you out more---Probably helping to alleviate your problem also. I have mounted bar ends on nearly all of my Mt bikes and folders---changed position helps a lot.

I do not recommend major changes on a bike unless you have ridden it 3 times a week for 4-5 weeks. You will probably adapt to the bike. Unless you are over 6' the bars on the Uno will eventually fit you fine.

I also have a problem with single speeds because you cannot keep continuous pressure on the pedals (by pedaling) which take weight off both the seat and the bars.

If I were you and was going to change something I would go to the adjustable stem from Thor as they are really handy. Yesterday against a 12 mph headwind I lowered the stem on my Dahon the last 1.5" to get away from the wind. By the way I am 6'3".

I owned a bicycle shop for 30+ years---I have fitted bikes to thousands of comfort bike and mountain bike riders----the background for my advice.

PS I have been playing with an ebike conversion on one of my Mtn bikes---You will want a wider seat for riding an e-bike and a disc brake on the front of your bike and a really strong fork if you are going hub motor. If you go Bafang Midmotor you still gotta have a disc up front----DO NOT GO Ebike without at least a front disc brake.