The direct replacement for your stock tool head would be the Mini Aerostruder: https://www.lulzbot.com/store/tool-heads/lulzbot-mini-aerostruder-tool-head
With this tool head you won’t need the optional adaptor like you would on the SE tool head for the Mini 2. It has a 0.5 mm E3D hot end assembly. It will print both standard and flexible filaments.
The other options that are available are the HS, HS+, and HE tool heads all of which will also print Carbon fiber filaments because of their hardened steel tool heads. They will also require the optional adapter. Here is a list of there nozzle sizes:
The HS has a 0.8 mm nozzle and had pretty good detail.
The HS+ has a 1.2 mm nozzle and is used more for rapid prototyping.
The HE tool head is 0.5 mm and is the stock tool head for the TAZ Workhorse. However there are no filament profiles developed for that model so you would have to do some testing. If you purchase this tool head, you would have to set up your Mini to use the SE tool head and then start by raising the temperature of your tool head by about 10C to start. Hardened steel requires a hotter nozzle then the brass nozzle on your current tool head because of its density.