Unless I was mistaken, the spirit of the PowerPC forum (and the Early Intel forum) strives to dispel idle speculation or uninformed guesses with folks trying out new solutions, providing how-tos, and sharing that knowledge with the community so that other folks can benefit. Atop all this, offering encouragement to community members who take the initiative to make things happen on their gear is kind of central to the lifeblood of this community.
Intell’s remarks weren’t being very helpful here, and honestly I lack a lot of patience for naysayers when they’re not, at least, trying different things with their own equipment and reporting on their findings.
As for your iMac G5, returning to the spinning rust would bring the Mac closer to OEM condition. Alternately, finding a decent 2.5" SATA-to-m.2 adapter and using a SATA m.2 SSD is a solution I use for my older gear. I prefer this over a 2.5" SATA SSD because the options for the m.2 form factor these days is generally broader and the pricing per GB tends to be slightly better. That said, the WD Green SATA SSDs are a pretty good value.
Lastly, if you haven’t bought another SSD solution, you could probably save extra money by forgoing high-demand premium brands like Intel or Samsung for a Mac which will probably not return to daily driver duty. Brands from the PRC, like Zheino, Dogfish, and Recdata, have been on the market for a while, and their overall quality has generally been positive with community members here (in fact, my PowerBook G4s have been using Dogfish m.2 SSDs since 2019 without any trouble). Both are set to hibernate mode when I put them to sleep, and they restore to wake much faster than an HDD would.