So... It seems like the Reds have exactly three "reliable" starting pitchers: Hunter Greene, Nick Lodolo, and Graham Ashcraft. After that, it's retreads like Luis Cessa and Conner Overton, and flawed, fringy prospects like Justin Dunn and Brandon Williamson. Look, full disclosure, it's gonna be a bad year and no one really cares that much about the outcomes of games. That said, lacking the talent to compete with top (or middle, or bottom) tier teams, maybe the best bet is to try to innovate and squeeze some extra scoreless frames out of a subpar staff.
Why use an opener? - The basic principle is that you have a guy - let's say a Williamson or Cessa - who's max is to face about 15 batters. This can be because they have mediocre stuff (Cessa) or because they walk dudes and throw a ton of pitches (Williamson; Dunn). Facing 15 batters means facing six batters twice, and three batters once. Allowing your "bulk" pitcher to enter in the 2nd inning means the three batters he'll face only once are likely to be 1-3 or 2-4 in the opposing lineup. You can open with a short reliever with better stuff to face the first 3-4 hitters, and in the 6th inning, when those batters come around for a 3rd time, you're already into your high-leverage bullpen arms. At the end of the day, you get maximum value from a mediocre SP by having him face the lower-order hitters more. He gets more outs, but faces less leverage.
The Reds have a good staff for this strategy - Tejay Antone and Tony Santillan are both career SPs in the minors who have undefined roles in the 2023 bullpen. There's no reason those guys can't start three to four games/week on a one-inning/5-batter basis. This allows you to space out your young guns (Greene, Lodolo, Ashcraft) and play matchups to maximize their development. Use Dunn, Overton, and Williamson as bulk guys. You can piggyback them. Get creative.
It's a DH world - you're going to carry 13 pitchers. You don't need a deep bench. Archaic, well-defined bullpen roles are a luxury a bad team can't afford. All that matters is getting the outs. Since it's blatantly obvious the Reds lack a #4 and #5 SP, the best thing to do is to be creative. Running guys like Dunn, Williamson, Overton, and Cessa out there as traditional starting pitchers is definitely going to fail. Using them as bulk guys/opener will likely fail as well, but at least it's acknowledging the talent deficiency and trying to do something about it