The claim that ALBM development was spurred by the inability of the H-6 airframe to provide the same capability as the B-52 or Tu-95 is reasonable, I think. If the H-20 was developed as a B-2 counterpart, to strike CONUS it would need to cross through US allied air defense networks in the 2IC, or Russia. Over in the strategy threads I have seen some fan-made graphics showing H-20s or H-6s taking off from Russia, but resting the fate of an entire strategic capability on a foreign country does not sound like something China would do, no matter how friendly that country appears to be at the moment. In a worst case scenario Russia might be unfriendly some day.
Using ALBMs to avoid the densely defended northerly routes across the Pacific makes sense, given the PLA's penchant for self-suffiency. ALCMs just would not cut it; Tu-95s and Tu-160s still have to penetrate North American airspace to launch their missiles, it's not like they can hit CONUS from inside Russian territory. ALBMs also have better survivability, as while a barrage of cruise missiles could be intercepted by NORAD's various fighters, Golden Dome is just a pile of paper. ALBMs could get through literally unopposed (after being launched).
The point of ALBM is:
(1)significantly extend range,
(2)delegate penetration to missile at the same time, as H-6 isn't survivable and can be tracked by anything which has LOS of it, from afar. Even at low altitude over sea.
This isn't mission that requires a deep stealth bomber. It requires "just" passing by Japan southern island chain(or north of home islands, or over empty eastern Russia), preferably at low altitude (to make coastal radars irrelevant). For that we need reconnaissance, strikes at key fixed radars(tower mounted ones), and medium range fighter escort in and out; even H-6 can do this well enough. After we pass Japan, interceptors aren't effective anymore(they don't have neither speed nor fuel to catch transsonic bomber in a rear chase), ALBM itself can be launched from a huge arc away from CONUS, spanning good ~10k km. This is beyond any effective fighter patrol.
Whole mission profile is perfectly viable with current force structure.
Starting in early 2030s, add in J-36s, which can do roaming interceptions beyond japanese islands, and add taste to interceptors' life.
Then we come to new aircraft.
What is VLO flying wing (i.e. all aspect, broadband stealth VLO)?
1, aircraft that can expect that it can't be tracked over long distances by means of airspace observation. That includes lower frequency radars.
2, aircraft that can normally expect to be aware of normal means of airspace observation long before those will be able to spot it by itself.
3, very efficient aircraft. We often forget, that before stealth, flying wing is just damn efficient at flying...provided you don't want long deep bays (see where it goes?).
4, through those 3 advantages, VLO bomber can employ smaller, shorter range effectors together with onboard means of reconnaissance, targeting and post strike evaluation, wastly increasing value of each succesful flight.
TLDR: this is penetration aircraft, built specifically - for a lot of investment - to operate over States. Which is reasonable, b/c for all their forward-deployed toughness, contintental US are suprisingly soft. There's ironically some merit in B-2 like sacrifice towards low altitude flight, because it just makes things easier near island chains. But if you're sure you're to remain stealth enough over the spawn of design life - no need really.
If you want "just" a better ALBM carrier - you aim for what Blitzo brought in many pages ago. I.e. this thing:
It will pass by Japanese island chain (especially since its it's stealth is mostly directed upwards!), and through very shape of the aircraft it's going to be massively easier to fit one long bay. Range requirement is greately reduced just because we rely on stand off. But again, that's just one launch attempt of light warhead per sortie, without even pen aids. No combat search, no strike evaluation, just 1-2 launches "somewhere", crew has no idea where even.