As I said before, I have made the calculation. I based it on a TOP 35 list from March:

https://www.nintendolife.com/news/2021/03/japans_35_best-selling_switch_games_in_the_first_four_years_according_to_famitsu

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.

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.

9.37mil: ACNH

5.41mil: SSBU

5.34mil: PokeSwSh

4.80mil: MK8D

4.69mil: Splat2

3.20mil: MHR

3.00mil: Momotaro

2.81mil: RFA

2.80mil: Minecraft

2.66mil: SMO

2.52mil: BotW

2.45mil: SMP

2.15mil: PokeLGPE

1.43mil: SMM2

1.31mil: NSMBU

1.20mil: Clubhouse

1.00mil: LM3

1.00mil: Kirby SA

1.00mil: SM3DW

0.96mil: SM3DAS

*Minecraft hit 2mil physical and was digital only a year before physical came out

*MHR is easily over 3.2mil possibly 3.5mil+
SM3DW isn’t official but it’s easily clearing a million

Momotaro was announced by Konami twice. First time I think was shipment and second was sell thru

I am not really asking about Momotaro specifically.  I want to know, in general, how you determine total sales of third party games in your prediction.  Do you have some physical:digital ratio you are using as an assumption?

Any updated numbers to see if this tbone prediction was bold enough?

Ah, good question. Let's update the table. We have current Famitsu-numbers for the games that still top the charts (and going back a few weeks for titles temporarily missing the charts). And we have the TOP 100 for 2022 to fill in some gaps.

I colored the TOP 20 for each time, if the cell is empty the value to the left (the last known number) was used for the sum.

So, if we assume a third for digital sales then we are at about 88M. Wonder might sell enough to enter the TOP 20 and replace Super Mario Maker, but at this point all games are already million sellers. So it is pretty close to the 100M.

If we look at single games in the initial prediction though it is more spotty. ACNH is far from the predicted 12M, it is 4.5M short. SSBU is about 2.5M, Mario Kart about 1M short.