No name brands like that generally offer very cheap and low quality components. They are built for less than $100 each and not with longevity in mind. The companies offer warranties that are just straight up bullshit. If you have any problems with a known brand product you buy from a legit bike shop, they will want to fix the issue. It's not in their best interests to release poor quality products when the market is flooded with so many great bikes. No name brands don't have to worry about that kind of thing because their target market is n00bs that don't know any better.

As far as specs go, they don't really offer specs. Established brands like Fuji, Trek, Giant, Avanti etc don't just use no name components. They use one brand that specialises in wheels, another brand for the brakes, another brand for tyres, they actually specify the type of Frame material etc

Here is the specs list for my Avanti:

Frame: ADT 4130 Cr-Mo
Fork: Cr-Mo with 1-1/8" Steerer
Brake Levers: Tektro XL-750 Alloy
Crankset: Lasco Alloy with 46T 130pcd Chainring
Brakes: Tektro R310 Alloy Dual Pivot with Cartridge Brake Pads
Hubs: Joytech Alloy Track Nutted
Cassette: 16T Sprocket & 16T Freewheel Reversible
Handlebar: Alloy Bull Horn 25.4mm
Grips: Zero gum wrap
Handlebar Stem: Alloy Ahead 25.4mm
Pedals: Nylon Platform with Velcro Straps
Rims/Wheel Set: Weinmann DP-18 32H
Spokes: DT Swiss Stainless Steel
Tyres: Kenda Karvs 700 x 25c
Saddle: Zero Solo
Seat Post: Alloy Micro Adjust 27.2mm
Bottom Bracket: Shimano UN26
Headset: Alloy Aheadset 1-1/8"
Chain: KMC Z-510HX