If you want actually minimalist, buy a sturdy townbike, or maybe a hardtail mtb, get ride of all other bikes and any bike-specific clothing (including shoes - use flat pedals). Maybe keep a helmet and lights. You don’t need a training setup, just ride your bike outdoors whenever you want. Millions of people live happily like that.
With regards to tools for maintenance etc, I find the modern ‘minimalist’ idea basically trades owning things for buying someone’s services - you don’t need any tools (bar a pump maybe), just take your bike to a shop whenever anything needs doing.