I made fermented hot sauce once, and i don't think it was sufficiently different to other kinds to be worth doing again. But then, i have only done it once!

I think my favourite hot sauces have started by drying the chillies, then toasting them in a pan. This adds a lovely smoky, rich flavour.

In terms of other additives, i recently made a rather long winded rum and coke themed hot sauce, the main lesson from which is that orange peel goes amazingly with chilli. I am now thinking about a chocolate orange hot sauce, built around toasted chillies, orange peel, and cocoa powder perhaps. Can i make an orange peel oleo saccharum using citric acid, and use that instead of vinegar? Should i make it oil-based? Use crème de cacao?! Much to ponder.

If you're going to grow your own chillies, i can highly recommend NuMex Bailey:

https://cpi.nmsu.edu/_assets/documents/Bailey.full_.pdf

It's a pequin pepper, so very small, but hot and with good flavour. This particular strain grows like the clappers, forming a compact, dense bush, which is covered in flowers and then fruit, which as the paper says, are very easy to pick when ripe. The productivity in terms of mass of fruit per unit of pot area is far better than anything else i've grown. It seems to be impossible to kill, too.