The whole aftermarket key ecosystem, even vehicles going back 20 years, is messy, horrible thing.

It's dominated by Chinese manufacturers of specialty tools (Autel, Xhorse, ...), which inevitably mandate bundled accounts, subscriptions, mandatory cloud features, etc. Even the older cars, you have either cheap Chinese tools, where you never know wheather it'll really work, or the manufacturer's tool which needs a dealer code, which of course the dealer won't have after 20 years.

I wrote about my 20 year old car-key-adding adventure here: https://jonas.bike/low-cost-diy-key-/-transponder-for-my-200... - it requires desoldering an eeprom, two pieces of hardware from aliexpress which come with pirated copies of software, and lots of hope that it'll work...

An open source community curated collection of scripts, which works with a cheap OBD dongle (which is all the chinese devices are: OBD hardware + per-car software), would be amazing.