Update 20.03.2021:
Flüelapass instead of Berninapass and Splügenpass. No border crossing to Italy.
Route
1300km / 27,000m vertical climbing
Roads
Mostly paved roads, some gravel sections may be possible. Roads with no or not much traffic and cycling routes. 28mm tyres should bring you to the finish without problems.
Big climbs
Nufenenpass (2478m), Furkapass (2429m), Sustenpass (2260m), Grosse Scheidegg (1962m), Col du Pillon (1546m), Col des Mosses (1445m), Mittelberg (1632m), Chasseral (1607m), Kunkelspass (1357m), Lenzerheide (1550m), Albulapass (2315m), Flüelapass (2383m), San Bernardino Pass (2026m)