How to get from Geneva Airport to Metabief, Doubs, France by public transport?

Google Maps don't find any connection between those points.

https://www.rome2rio.com/ suggests taking trains to Vallorbe and then a taxi from Vallorbe to Métabief.

(Actually rome2rio suggests a taxi from the station just before Vallorbe, but it's probably going to be easier to find a taxi at Vallorbe, which is a larger station).

As noted in the comment thread under your previous question, this taxi ride is not long, but since it does cross a border, you should agree on a price with the driver before getting in.

Alternatively, if you don't want the adventure of negotiating a cross-border taxi ride in Francophone Switzerland, you could take a train all the way to Frasne on the French side, and then the bus from Frasne to Métabief. (You've found the timetable for this bus already).

This will most likely be more expensive because you'll need the TGV from Lausanne to Frasne rather than a local Swiss train, and certainly slower. Note that the TGV requires reservation, but on the other hand you shouldn't need to worry about flight delays because the first connection you can get leaves Genève-Aéroport only at 11:32 anyway. Arriving in Frasne 13:14 you then have an hour and a half to kill before the bus towards Jougne departs at 14:49

Here are some options. What time can you actually depart? (possible arrival delays, disembark, immigration, customs, get kerbside). You only told us your plane arrives 07:30. So I priced departures for 08:30.

1. Train to Vallorbe (CH) is one option and the most reliable for schedule, dependability. You still have to arrange to get from Vallorbe over to Metabief (ride, taxi, etc.). Be aware the CHF 24.60 price with SuperSaver discount is for a specific day & time; if you miss it (e.g. incoming flight late), your ticket is no good and you have to pay standard price.. The undiscounted price (1 adult, 2nd class) on sbb.ch for Geneva Airport-Vallorbe is CHF 41.

2. Another option is Blablacar long-distance rideshare. Note: this may be cheaper but it is seriously less reliable: a rideshare service that matches prearranged passengers to drivers. Unless you will have functioning phone+internet service and basic French and you're prepared to post your trip request a month in advance and sift through trip proposals in advance, only use highly-rated drivers with good reviews, and you're ok with occasional driver no-shows, don't use this.

   • You register on Blablacar app/website and post your requested trip (from, to, date & time). Each driver posts their own ride offers with requested price, typically a few days or weeks out. Three months out is too far. The app sends you matching trips, you message individual drivers and figure out which offer to accept, look at their reliability. All payment is via the website. Drivers will typically aim to have 2/3 passengers per car, so a lot less room than train. You might be able to get them to change the destination by a few miles to suit you, I don't know if you can negotiate slight extra payment for that. You'll need to know a realistic departure time and they won't wait if you have a flight delay.
   • Looking at prices of current offers on Blablacar for a comparable trip this month: EU 8.50-9.50 for Le Grand Saconnex (= Geneva Airport) - Les Hôpitaux-Neufs, 25370, France (2 miles from Métabief).
   • Blablacar is not at all user-friendly if you don't know the geography, it justs lists trips by placename, no map view, no postal code, doesn't show you how close/far those placenames are to your requested destination.

3. Train all the way to Métabief just doesn't seem to make sense. According to SBB.ch, Genève-Aéroport - Vallorbe is only 1 train change and 1h45-2h, but Genève-Aéroport - Métabief undiscounted is CHF99, with 2 train changes and takes 4hrs (or CHF69 with discount).