If you are careful, you don’t need anywhere near that power. Make sure everything is off and don’t move electric seats etc.

When I was getting coding done on my f36, the power supply was showing 25-35 amp draw with everything switched off but ignition on.

A 25 amp power supply would be a little skimpy but you might get away with it. Use it to make sure the battery is fully charged before you start.

Gys flash power supplies are used by a lot of dealers and professional coders. Something like this 50 amp would do the job nicely:
https://www.gys.fr/prod-026056-C106/....5M_CABLES)/en