Is there a way to have it so ps does not open with the default “fit on screen”

Yes i was able to replicate the issue on a 2017 iMac with a 21.5" 4096 x 2304 Retina screen running macOS Monterey 12.7.4

in Photoshop versions 2022 (23.5.5), 2023 (24.7.3) and 2024 (25.7), even resetting the preferences in Photoshop 2024 to see if that was the cause.

It was not.

There are so many variables involved, so it's tough to narrow it down to one cause in as far as a user can control.

For example, on this particular Mac turning off the Rulers worked, but so did changing the UI Font Size in the Photoshop>Interface preferences, removing the Timeline and Measurement Log from the bottom of the Photoshop interface and even changing the Display size from Default Display Size to Scaled Smaller and Larger in the Apple>System Settings>Display.

The size of the image made a difference as well, as images right around 4000 X 6000 give or take a few hundred pixels exhibited the issue your having while smaller and larger images in terms of pixel dimensions did not.

If you turn off the Rulers and/or change some of the settings in Photoshop 2024>Settings (Preferences) like the UI Font Size in the Interface settings or uncheck Large Tabs in the Workspace settings you might tweak it enough to have the image fit on the screen with space without having to Cmd 0 after opening images.

Whether or not there is bug in Photoshop, Adobe will have to make that determination.

Photoshop 2024 (ps ver 25.7) Rulers On

Photoshop 2024 (ps ver 25.7) Rulers Off

Photoshop 2024 (ps ver 25.7)

Photoshop 2024>Settings>Interface>UI Font Size set to Large

This can be automated via an action or script using the Script Events Manager:

https://prepression.blogspot.com/2021/10/photoshop-script-events-manager.html

What version of Photoshop 2024 do you have?

From within Photoshop go to Help>System Info and read the top line Adobe Photoshop Version.

I would not use it, but you could try Window > Application Frame. 

Cmd 0 is fit on screen. Can you show a screenshot?

Normally it will open at the largest of the ratios available in the cache that will still fit on screen. It normally doesn't open as "fit on screen", but slightly smaller.