Gargants are "Titan Class" and since they don't intend to include Imperial Titans I can't see them including Gargants...maybe a Stompa at a stretch.
Squigoths are also an artillery piece in Titan Legions, they don't (or didn't when I played 40k table top) appear in 40k table top. They are in the same power and size catagory as a Baneblade. Way too big for this game.
I want the Flash Gitz gun to be a frame that has multiple "gun modules", I.E., you can build your own extra killy shoota by taking the body and slapping on Shoota barrels, Burna Barrels, Rokkit Launcha bitz, Zzap Bitz, ect.
Yeah but the problem is that to be able to make one of those you'd have to be prepared to spend 6 months of your gaming experience being run over by one of the original ones every 5 minutes...
I think it'd be a good idea to have central "types" of deffguns (beamy, dakka, etc.), and then have different variants of those guns with just cosmetic changes, based on how many of certain types of enemies you kill with that weapon. For example, you have an anti-tank deffgun, you go to a battlezone with mainly marines and live to see through to the end of the battle, after the battle you gain a looted lascannon as your deffgun. It'd be a good way to make it feel like you're looting, while only keeping it balanced as only a cosmetic change.
They gotta make an upgrade on vehicles or even weapons that makes them painted red. Because everyone knows what happens to da red wuns...
Just get the proppa ork version the skullhamma I like this conversion for it the most I personally want Burna Boyz