You're looking to make 2-way hands in this game. So in the first example, your hand on the flop is a made nut low which has minimal counterfeit protection, and your only draw to high is a gut shot that isn't the nuts. Thus, this hand goes down in value quite a bit, and you should be trying to keep the pot as multi-way as possible, or you should check/fold to any serious action.
In the second hand, your hand is much stronger. You have a strong two way hand. On the flop, your nut low draw cannot be counterfeited. You have TPTK for high, which can turn into jacks up/aces up by pairing any card in your hand (which also puts out a low). You also have a gutshot. On the turn, when you make a 2-6 straight plus the nut low, I'd be very happy shoving my stack in, especially at these stakes, since you only lose to the nut-nut hand.
Preflop, there are two reasons to raise. First, raise for value, and secondly, raise to control the number of players in the pot. Since hands in PLO8 run very close in value preflop, you want to do less raising for value, and more raising to buy you position/knock players out.
A hand where you would want to knock out players would be something like A♦
4♠. Heads up, high hands go up in value, and your low draw becomes less important. So I would raise AKQ4ds because you have lots of strong high potential, and this hand plays better against less opponents. If more opponents enter the pot, the odds
of you winning with 2 big pair diminishes, and the odds of your 2nd/3rd nut low winning are also smaller.
Hands like A♦ 2♦ 3♥
6♠ are what players call "pulling hands". They have super strong low potential, and thus you'd prefer that the pots you play be multi-way. This is really more of a limit concept, but the point is that the only time you'll want to put your stack in with this hand is with the nuts (a flush & the nut low for example).
And obviously you can raise your AA2X, A2KQ, A2KK, A23Kds type hands for value preflop.