I din’t think they are multi-function levers. Just brakes. Bar end shifter. Interesting contraption. Super long bars. I’d hit my knee on that. Saddle super low, frame probably too big as you say.
Garmin mount seems to hop around between photos too.

1x with that small chainring is not going to keep up with any records but for just a bit of fun, prob quite low maintenance.

edit; I notice luizphillipem said “shifters” plural. Well if you put a front shifter on that, you also need a cable, derailleur and new double front crankset. That’s not going to be under $300 total.