So to clarify, battery resting voltage is low and you're getting what appears to be intermittent charging? You said the voltage would jump around when the truck is running right? I've had that happen once in the Suburban. It turned out to be the battery cable connections. They looked OK to my eyes, but I cleaned and reassembled them and the problem went away. I did have an Optima YellowTop develop a weird internal problem in the red truck many years ago. It would behave normally, and then just refuse to start out of nowhere. Pretty sure one of the side terminal connections had cracked internally, you could wiggle the cables and get power to come back.
My Odysseys have been rock solid, I've only replaced one of them and IIRC it was around eight years old. Still started the Suburban... It was just reading low on my cheapo Harbor Freight load tester. The one in my red truck is older than that and still kicking.
Speaking of which... If you want to test the health of the battery yourself those load testers are pretty affordable. I think mine was around $40 and I've used it more than I thought I would. The Odysseys are right on the limit of the cranking amps the cheap ones are designed to test (mine smoked pretty spectacularly the first time I cranked it up) but they seem to work fine as long as you can get a solid connection with the flimsy clamps. I just looked for them on the Harbor Freight site but it looks like the listing is gone. Strange, but you can some that are similar on Amazon if you search "500A Carbon Load Tester." IMO a good tool to have around, especially if you have multiple vehicles that use 12V batteries.
www.amazon.com/VCT-Battery-Alternator-Starter-1000CCA/dp/B082BHB9SH