I believe it supports USB flash drives up to 256GB. The drive though has to be plugged into the port in the center console. It supports various formats including mp3, aac/mp4, and FLAC. You can have your music organized in sub-folders. I figured out that it supports artwork up to at least 800x800 (I didn't test anything higher because that is the max my other car supports) but it doesn't seem to recognize artwork embedded in the file (at least not for FLAC files). Instead the artwork has to be called folder.jpg in the folder of the music.
The bad part about only being able to plug into the center console port is that there is only one port. If you want to use something else like Android Auto/Apple CarPlay in conjunction with your USB Flash Drive, you can't. I even tried connecting a USB Hub into the port and it actually gave me an error message on the screen that USB Hubs are not supported. I wish it was like my VW Passat that has memory card slots in addition to the USB port.
Regarding ripping, you can "rip" to the internal drive, but you have to specify it to specifically do so. It's not actually ripping but copying the files to the internal drive. If you do that then you can pull the USB flash drive and play music from the internal drive. However the drive is extremely small (I estimate around 8GB) and I have had some problems with it.
For example my music library is in FLAC format. FLAC files are a lossless format vs. a lossy format. Basically what that means that is that with lossless formats the file is compressed but no information is lost. The music files retains the same quality as the the original CD. With lossy, for the sake of compressing better, some information is lost and technically the music file is of inferior quality than the original. However it compresses a lot better. To give you an idea an MP3 file of around 5-6MB will probably be around 30MB in FLAC, where the original file will probably be around 60-70MB.
Since storage is is so cheap now days (I can get a 256GB flash drive for $50-$60 now days), the larger size of the FLAC files is not a big deal because I can still get a large music collection onto a 256GB flash drive in FLAC format.
Now the reason I get into all of that detail is because of two limitations of the internal storage on the Honda Odyssey. With the 8GB storage on the Odyssey, it is very limiting if you are using FLAC format. You could probably only get somewhere between 10-20 albums on there. The other problem I ran into was that the Odyssey does not seem to recognize files of a certain larger size when copied to the internal drive. I copied a small portion of my FLAC collection to the internal drive and the result was that it only recognized a small subset of the music I copied. Taking a look at what it did recognize it was all shorter length songs or intros (maybe under a minute?) It wasn't a format issue with the FLAC files because it did play/recognize the shorter length songs, and the same songs it wasn't recognizing on the internal drive played just fine off of the USB flash drive. Very strange problem but I really decided not to pursue due to the small drive size in the Odyssey. Because of this I really never determined what the cut off size/time was on the files before they started not to show or play. Also I am pretty sure that checking the file manager on the head unit, I did verify that the files were copied over. They just weren't recognized or played.