I havnt looked, personally. However the concensus is its true on forums (neogaf mainly).
The nintendo fans are quick to say "its like that on every system", and its true, every system has shovelware.
However skipping past the degree or amount, of which there are of such on the system.

Switch likely has more than most, but its just ignored.
I remember seeing a thread, that talked about how many mobile (phone) games the Switch actually got.
Supposedly back in 2019, there was over 500 of them on it (according to the thread).  I'm 100% sure the same isn't true for the PS4.

I'm skeptical that a storefront that allowed Life of Black Tiger has significantly higher quality control standards than the eshop.

They are equally bad at quality controll.
However that doesnt mean, they both have equal amounts of it.

Like I mentioned before, that thread about 500+ mobile games on the Switch.
I think part of it might be its arm based cpu, which alot of phones use.
So its easier to get a phone game running on the switch, than say a xbox one or ps4.

I'm still not seeing any actual quantification here, just "people on forums say x". People on forums say a lot of things. They spend all last gen saying there were no good games on Wii yet that was false.

https://www.youtube.com/watch?v=yXGIXBO0lZM

I'll try and find that thread (dont have it bookmarked), that mentions the share amount of mobile games, the Switch was getting.
Like I said, back in 2019, that went past 500+ mobile games, and the thread was about nintendo fans not being happy about it.

Edit:

Here is a thread about the matter (not the one I was talking about though) :
https://www.reddit.com/r/NintendoSwitch/comments/aostds/list_of_mobile_games_ported_to_switch_ver_20_will/

Here is a old spreadsheet document, that lists every mobile game the Nintendo Switch had like 1+ years ago:
There is 450 games on it.

https://docs.google.com/spreadsheets/d/1Lk6FMOOsJZh3aAuOyLgYanr9Y4hWqtiY1IPokbcaNss/edit#gid=0

Are you also going to provide a list of PS4 shovelware?

tell you what, if you find out that the PS4 has like 500-1000 mobile games,
go ahead and post a spreadsheet doc, listing all the games, like i just did above.

Has someone actually documented the number of shovelware games on PS4 though?

If there's no such list, that is not evidence that shovelware isn't abundant on PS4, simply that nobody has sat down and counted it. 

Clearly there's no shortage of it.

Successful systems always get a ton of shovelware, Switch isn't at all unique in this regard.

This myth has been going on since the Wii/DS era to try and win a rhetorical victory based on opinion in the face of getting smashed by both of the Nintendo consoles, who took #1 and #2 positions based on the fact of superior hardware and software sales. Another fact of that generation is that it was the most successful in the history of dedicated gaming devices, and Nintendo took home gold and silver. Yet another fact is that Nintendo offered new ways to play classic games as well as provided new avenues to explore new types of games on both Wii and DS... basically, Nintendo won because people were more interested in creative experiences rather than the same-old formulaic clones that were shovelled onto the PS3 and Xbox 360.

Does this mean my theory Microsoft has far more aggressive curation protocols is right?