Could you post the current Famitsu Top 20 into the OP just to have an idea on where we stand right now?
As I said before, I have made the calculation. I based it on a TOP 35 list from March:
You can take this and replace number with the current ones. As the last week saw some new releases and pushed out some evergreens from the list, I filled in some numbers from week 25. These are in italics. Also since then Monster Hunter Rise and Mario 3D+Bowser Fury replaced some titles at the end. For the future, if we assume BOTW2, Pearl/Diamond, Legend Arceus and Splatoon 3 all do only half of what their predecessor did, then they all enter the list as well, replacing games at the end.
|March list||current numbers|
|Animal Crossing: New Horizons||6,625,026||6.807.289|
|Super Smash Bros. Ultimate||4,145,903||4.318.560|
|Mario Kart 8 Deluxe||3,656,140||3.888.483|
|Ring Fit Adventure||2,346,098||2.654.669|
|Super Mario Odyssey||2,208,475||2.241.841|
|Momotaro Dentetsu: Showa, Heisei, Reiwa mo Teiban!||1,846,039||2.242.440|
|Super Mario Party||1,818,405||1.918.488|
|Pokemon: Let’s Go, Pikachu / Eevee||1,772,856|
|Zelda: Breath of the Wild||1,771,235||1.829.389|
|Super Mario Maker 2||1,065,261||1.102.573|
|New Super Mario Bros. U Deluxe||1,031,494|
|Kirby Star Allies||878,800|
|Luigi’s Mansion 3||745,825|
|Clubhouse Games: 51 Worldwide Classics||630,909||734.237|
|Taiko no Tatsujin: Drum ‘n’ Fun!||572,215|
|Fishing Spirits Nintendo Switch Version||566,909|
|Dragon Quest XI S||560,075|
|Monster Hunter Rise||2.272.644|
|Super Mario 3D World + Bowser’s Fury||790.477|
I striked out the last two, as they are pushed out of the TOP 20 by MonHun and 3D World.
If I add up the current numbers (and the old ones for the games that aren't topping current Famitsu lists) I get: 45,781,515. That is without digital. Assuming one third (15 million) is digital is not too far fetched, so 60 million seems fine. The publishers sometimes release shipped numbers including digital, if you have access to such, you can replace the numbers in the table and make another calculation.