No longer true.
Three are in operation atm, with 3 more originally planned to become operational before the end of the year (covid permitting I guess).

In operation:
Avia, Oberer Graben, St. Gallen
Agrola/Landi, Zofingen
Coop, Hunzenschwil

Planned, the first three to open this year:
AVIA, Rümlang
Coop, Dietlikon
Coop, Crissier/Lausanne
Coop, Bern Bethlehem
Agrola, Rothenburg
Avia, Geuensee

Avia, Coop, Migrol+Migros, Agrola+Fenaco (Swiss farmers' cooperation and supplier of Landi) formed the cooperation "H2 Mobilität Schweiz " (H2 mobility Switzerland). They shoulder the initial effort jointly of setting up a viable network of gas stations. They project having a sufficient network ready by 2023 (plan before covid hit, I seem to remember reading 600 stations). The cooperation members own 1'500 gas stations nationwide and operate 1'700 trucks and other heavy vehicles. Apparently 10 trucks enable a gas station to break even, so they kind of generate their own success.

The first aim is to have a working chain broadly along the Autobahn A1, from St.Gallen to Lausanne. While the target market are trucks and similar (350 bars) the gas stations will serve cars (700 bars), too.

The first ten Hyundai Xcient trucks were expected for September 2020. According to plans 1'600 more are planned by 2025 [probably replacing the current fleet].

It looks to me like they plan to produce their own hydrogen, with focus on production near the station, and make it "green".