Yeah, I guess you have been here enough to know that BF is mostly a cesspool.
I would buy a Denali if it fit me, if I were in your situation. Like @
GlennR I commuted for quite a while on cobbled-together Frankenbikes I rescued form the garbage .... and I rode those broken beasts for thousands of miles each year.
What would make a bike "too bad to ride" would be parts So bad they didn't work (say, wheel bearing which let the wheels move sideways but nor rotate) or parts so broken by abuse or neglect they no longer worked. Otherwise, a cheap derailleur can still move a chain, and if the pedals and the bars turn .....
Biggest problem with really cheap bikes isn't even weight---I mean, everyone loved their old Schwinns which weight 42 or 46 pounds---but cheap parts which break too easily, don't stay adjusted, and cannot be replaced. Really cheap stamped brake systems---the levers are either the cheapest pot-metal and bend in a stiff breeze, or are the most brittle plastic and snap if you look at them---and cannot be replaced. No one makes or sells just the parts---to get more you need to buy more bikes.
Derailleurs so poorly cast, stamped or machined that they move even when you are not shifting. Cranks which snap under load, bearing races machined so poorly the bearings bounce instead of rolling ....and of course, some from the factory with zero grease and generally get ridden that way until they seize (if they are tight enough) or just pile up in the bottom of the race.
On top of that, people who buy Denali-level bikes usually don't think about maintenance. Ride it, and when it breaks, replace it.
My advice is to get some simple tools, get that Denali, watch a ton of YouTube videos .... and start keeping your eyes peeled for other junk bikes. If the Denali's frame is the right size, you are golden, because that frame will last until the next Ice Age. And generally, all the really cheap bikes have the same standardized parts specs---whatever was in use 40 years ago. That means most stuff can be shared among bikes---even mountain-bike parts on road bikes with a few exceptions.
Pretty soon you will get good at assessing junk bikes---what size wheels it has, what components are too beat to bother with, what might be salvaged, what will and won't fit your bike and your needs---and in a while you will have boxes of useful crap so that you can keep your bike running without going to a bike shop and coping with the scorn and also paying for it in cash.
As @
70sSanO says .... clean and grease the bearings wherever you can. Bottom brackets (you can possibly get in there without specialty tools but it is tough---but tools are really cheap) and wheels and to a lesser degree headset----Those are generally neglected and when they die they really hurt you (because it always happens ten miles form home on either a blazing hot day or a rainy night when you have something really important early the next morning.)
Best thing to do, if the bike fits you ... . buy it and continuously post threads---with lots of pictures---about how much you like riding it, how you depend on it and it always comes through, how much better it is making your life, and what a great ride it is. Drive people crazy here---they deserve it.
If you ever have the time and desire---do a Gran Fondo or a longish charity ride or a metric century or something, because the bike snobs here will tell you--despite evidence---that it cannot be done. Watch the heads explode!