More jazz-blues fusion than psychedelic and in the tradition of beatnik cafes in the 1950s.
This kind of jams also influenced many rock bands, one of which is The Grateful Dead with their improvisation.
Music is indeed derivative, if not in chord progression, in style, or at the very conceptual level.
Thanks to ChrisGoesRock #125 for making this accessible.
AllMusic review of the album by Mark Deming:
Moby Grape‘s two greatest strengths were that the five members of the band were all top-notch musicians and great songwriters. Grape Jam amply demonstrates the former virtue, while the latter barely figures into the formula at all. As the title suggests, Grape Jam consists of five semi-improvised selections in which the players stretch out at length, primarily on slow, blues influenced numbers, with plenty of ace guitar work from Peter Lewis, Jerry Miller, and Skip Spence, while Al Kooper and Mike Bloomfield sit in on keyboards for a few numbers. While there’s some potent soloing here, and the rhythm section of Bob Mosley and Don Stevenson show they can adapt to whatever the band throws their way, the tunefulness and tight performances that made Moby Grape one of the finest debut albums of all time is missing in action. As good as the chops on display here may be, great soloing doesn’t mean all that much without the context of a good song, and that becomes painfully obvious on “Boysenberry Jam” and “Black Currant Jam.” Grape Jam was originally released as a companion piece with Moby Grape‘s overcooked but compelling second album, Wow (folks who bought Wow could get Grape Jam at a discount), and as a bonus item it’s not without interest, but all by itself this meanders far too much for its own good. Grape Jam is akin to hearing a handful of talented musicians goofing off, and while the talent is obvious, so is the aimlessness of the music.
For more info about the album visit: https://www.discogs.com/Moby-Grape-Grape-Jam/release/1165568