RalphS has nailed it. If you have never even shot a .44Mag, you don't need a .454. Lots of folks like to quote the USFA study that was done back in the `80's and conclude that the .44Mag (and .45-70) are poor bear stoppers but that the 220gr .30-06 is king. If you consider the poor loads they used for testing, this is true. Step up to proper loads in both and you have two cartridges that do a better job than the 220gr .30-06 (Remington CorLokt) they used in their tests. That would be a good 320-355gr LBT in the .44Mag and a 420-500gr in the .45-70. Forget the .454, it's a lot of pressure and recoil that produces a lot of velocity but practically, only serves to flatten trajectory. Same for the .460 and .500S&W. They are more difficult cartridges to master and won't yield you any gain. You're already against the wall just starting out with the .44Mag. Although the .480Ruger is a very practical cartridge, it's probably still a little more than you need right now.
Shotgun slugs are pitiful.
If it were me in AK for 6mo, I'd get a S&W Gov revolver. It fires .45acp .45LC & .410 shotshell....For a semi auto, I'd seriously consider a Glock 20 10mm with the Guncrafters Industry .50GI kit.
You can handle bears, wolves, critters & ___er
I would recommend against both the Governor and the .50GI. The .410 is useless for such purposes and the Governor is not a very good general purpose woods gun. It's not strong enough for appropriate .45Colt loads. Poor choice. The .50GI is a very moderate big bore that does not utilize heavy enough bullets for bear duty. You'd be better off with the 10mm and 220gr loads from DoubleTap.