2h sounds dubious
No, not really.
4.8cuft is about 135l.
10lbs is about 4.5kg.
That - first of all and most importantly for drying - gives you the 1:20 ratio conventionaly regarded as required for fast and even drying.
Then, an EU stand alone heatpump dryer can dry 4kg of laundry spun at just 1000rpm (60% residual moisture) in about 90min.
This has probably a 1200rpm spin or higher in a bigger drum, getting you 50% residual moisture or less.
Given that most washers on the US market offer some kind of TurboWash equivalent, 30min for a wash and 90min for a dry seem reasonable.
I think that 120-180min is reasonable for most loads in this device, dry to dry.
A heatpump dryer can be surprisingly fast - especially at 120V - if you have enough space to give it proper airflow rates and a big enough heat exchanger.
You can do that in 24" EU sized cabinet for a dryer alone no problem.
Now, this machine "only" has a 4.8cuft drum in what appears to be a 27" cabinet but with a greater height than normal and maybe even an inch more depth.
Leads me to believe they basically designed a 27" heat pump dryer base into a pedestal, then added some air flow channels into a 27" washer by shrinking the tub a bit. Stack it and connect it, done.
Basically any current EU A+++ class dryer can dry 8kg of laundry (17-18lbs) with only 1.5kWh of energy usage in less than 3h from 60% residual moisture - that's the energy label testing.
They use a 400W heatpump and a 100-150W drum/fan motor.
That's an equivalent heating/drying power of just about 1.5kW.
If you can fit just that into the cabinet, you are basically already there.
Biggest challenge is getting good enough airflow and fitting a lint filter somewhere.
But given you have the additional space of a 27" cabinet, I don't see why that isn't doable.
I do think the price is absurdly good for that kind of appliance though.
A normal TOL frontload washer and dryer are probably more expensive than that - and they aren't even heatpump.
I am also somewhat of the opinion that the only reason there aren't any good full size heatpump dryers out there for the US isn't price, technical disability or even cost per se.
It really is only the lower margins one would have to accept and the probably lower demand.
Given all that space in a 27" cabinet, you could easily beef up the heatpump power - the already high needed airflow comes natural to US dryers.