At this price point, you be buying a lot of features, but wheels that won't stay round or straight, cables that need adjustment all the time, possibly a headset that slips or a frame that fractures. Check brand forum known problems and solutions about any brand you intend to buy. Electric bikes under $1000 tend to use the parts that one finds on the cheapest kiddie quality bikes at discount stores. My diamondback MTB the wheels were so small the tires would fall off the rim. The shimano rear axle on that bike broke under my enormous 180 lb. My Pacific Quantum MTB, the plastic crank arm wore out at about 4000 miles. I couldn't get it off.
I'm one of the max cargo shoppers here, and I limit my loads to about 80 lb on 2.1"x26" tires. I have a bike I paid $2000 in 2017 with 2 bags, dual leg stand, & front basket, for before I put electricity on it for $840. Shown in picture. No wheel or cable problems. I broke a fender once with my foot. I don't believe in trailers, on streets, they are invisible. My bike has been hit twice by cars even with bright green paint on the ends.
Having burnt up harness on my best motor in the rain, I have downgraded to geared hubmotors I'm buying used for $36. I bought some 21 lb 36 v batteries from same shop for $75+60 freight but don't know yet if they are a bargain or scrap. BAE systems surplus. I finished the charger to 42.8 v last week. If I were starting out again I would buy another geared hub motor kit from ebikeling.com of Chicagoland. His batteries don't cause complaints either.
The cheapest stretch cargo bike I know of is the mongoose envoy. It is not powered. It would not be fun to carry up the stairs. My bike is 88 lb with motor & battery but no bags, tools, or supplies. There is a thread about the mongoose conversion down on diykits thread. My wiring is external and some here look down their nose at that.
I take my battery off the bike when it begins to freeze. It is back on again at the end of April. My battery is wrapped in white foam that it was shipped in, a plastic bag, and the charge & power leads are pointed down out of the plastic bag and have a drip loop. Enclosing all that is aluminum angle from HD screwed together with SS #10 screws & elastic stop nuts from mcmaster.com . Nothing like the batteries integrated into frames with the contacts pointed up at the rain. It is a generic 48 v 17.5 AH battery. I use insulated .250" flag terminals crimped off the wires, since the XT60 charge connector fell off. Dorman flag terminals are reliable, the crimp terminals from ***** melt out at 30 amps. Reverse the + & - direction so you can't plug it in backwards.
If you don't want to convert, the Blix Packa is small, 24" wheels, and has 3 complaints on the brand forum.
https://blixbike.com/pages/electric-bikes
I tried carrying groceries in baskets on a $150 MTB, and the weight made the steering unstable. Weight on the back lifts the front tire. I've been over the handlebars on my chin 5 times since 2008 on the MTB's and a cruiser with rear baskets. Last time I broke it, just before I bought the stretch frame bike 12/17. One time a dog attacked the front wheel and knocked the MTB over sideways spilling groceries all over Hwy 3.
I ride year round with varying amounts of clothing. I ride knobby tires year round, Kendas or Giants. These give me enough traction on snow, but nothing but spikes works on ice. I will ride at 6 deg F in Welles Lamont farmer mittens, oven mitts over, 3 pairs socks, 6 layers top and 3 layers pants. I use carhartt insulated pants under 15 F. Welder's helmet liner in my helmet, and safety glasses.
Ensure you have enough money for a stout security device to lock the bike up. Lots of threads about those on parts, also general forum. I use a 6'x1/2" SS sling and a Abus 92/80 lock around power poles gas meters & live 440 vac conduits. Not those cheapo sheet metal loops cities bolt to the sidewalk. One $2 wrench, bolt loosened, bike gone.