I implemented a similar project using Koto https://github.com/cornedriesprong/ohm. Not nearly as full-featured as Glicol, but I guess it can serve as comparison.
The algorithm was discovered in 1983, and for how computationally cheap it is, I'd say it's pretty convincing. Waveguide synthesis is a generalization of the same idea, often with more realistic results.
Variations on Karplus-Strong synthesis can yield some pretty wacky, dry and plucky types of sounds. In the original paper, the authors propose a variant of the algorithm which involves randomly alternating the sign (+/-) of every sample in the feedback loop, which creates a lot more atonal information in the signal. There’s also a variation floating around which uses an allpass filter in the feedback loop to introduce inharmonicity in the signal, see for example https://www.youtube.com/watch?v=SpC3t1EVF_Q.