Surprised no one has mentioned singlespeed yet :p. Bike-wise, I have an old hardtail on the trainer, a steel singlespeed hardtail (which is custom and has a lot of bells and whistles, to be fair), singlespeed cross bike and a BMX for the backyard pump track. I’m in the process of selling my geared full suspension that I hardly ever ride, and will probably give the cross bike to a local junior racer soon.
Training wise, just TR on erg mode with whatever the AI tells me to do and some metal in the headphones. Before AI it was whatever the standard plan told me to do. No thoughts, just pedaling. Since I started TR in 2018 I’ve added nearly 100 watts to my FTP, while being consistently inconsistent due to having 2 young kids and a pretty demanding job, so it’s worked ok.
I’ve got enough tools to adjust a derailleur, change a cassette and change tires, but that’s about it. Never liked working on bikes and will gladly pay the pros.
Where my minimalist streak really shines, though, is clothing. I haven’t bought anything new other than socks and gloves in probably 3 years, and regularly wear some bibs that are nearing 20 years old on the trainer- although my wife is starting to insist those be thrown out!