But I think OP's question is whether the physically larger BluRay media can be PLAYED in a conventional CD/DVD drive, simply as a larger version of a CD or DVD.
In other words, instead of reading a "data disc" (say containing MP3 files or video files in an ordinary folder/file structure recognized by Windows Explorer) limited to 700MB for CD, or 4.7GB/8.5GB for SL/DL-DVD, could a 25GB SL-BD be written (by a suitable burner) and then used as an ordinary "larger data disc" in mechanical players that can read CD/DVD?
I don't think they can... not unless the reader drive in that mechanical player can also read BluRay media.
In other words, if you have a mechanical drive that can only read CD, then it cannot also read DVD... even though the data on the DVD is identical in format and structure to an equivalent CD. It can only read DVD media if it is a CD/DVD drive, capable of reading both forms of physical disc media.
Similarly, although you can certainly create a very large "data disc" on a blank BluRay media using a BluRay burner, you will only be able to use that disc on a mechanical drive that can read BluRay physical media... namely a CD/DVD/BD combo drive.
Now it is possible to say write a "BDMV" BluRay movie onto a SL/DL-DVD media in true BluRay BDMV format (because the movie clip/file is small enough to fit even in BDMV form) and then insert that disc into a mechanical BluRay player and play it successfully. In other words if the BDMV file will fit on a conventional blank DVD, you can do that and it will play exactly as if it were on the more expensive (and much larger, but unneeded here) blank BluRay media and present all of the HD audio and video formats, exactly as if it were a true commercial BluRay movie. But the BluRay player drive can obviously read ALL physical media formats... BD, DVD, and CD.
So in order to be able to use a "data disc" written onto BluRay BD blank media, even if nothing more than folder/files written to the 25GB capacity disc by a BluRay-capable burner drive... you will need to have a mechanical drive in the reader/player which is also BluRay-capable. A standard CD/DVD drive cannot be used to read such a disc. You must have a CD/DVD/BD drive to read all of those physical media types.
Pretty sure this is the story.