I’ve been thinking of signing up for this class:
Alternatively via Interweave:
https://www.interweave.com/product/darn-it-how-to-repair-your-knitting-online-workshop/
The teacher, Jennifer Raymond, has a business in the US mending knitted and crocheted fabric.
Her blog is worth a browse if you are interested in the topic, or just want to marvel at mending:
https://www.tinkingturtle.com/blog/