To add more even more support for Charles-Tim answer, I actually found an article[1] - February 2021 - from someone who decided to test what would be the results that he would get by mining Monero on his Raspberry Pi (I think he used the 4). I'll jump to the part that I'm sure you're most interested in:
My Raspberry Pi 4 calculated 357 good shares in about 8 hours of run time. Miners are rewarded for good shares. Bad Shares are calculations where I came up with the right answer, but my Pi produced the results slower than another computer. Miners only get paid when they submit the correct answer first. Invalid shares are the worst as a miner is penalized for every invalid share due to possible fraudulent activity. I was a bit worried when my first 4 shares were marked as invalid shares.
357 good shares = 0.000001410642 Monero = 0.00015569 USD
I made the equivalent of 1/100th of a penny in 8 hours.
In order to withdraw my Monero, I needed a minimum of 0.05 Monero, approximately equal to $5.811 USD. (Exchange rate at the time of the writing of this article.) At a pace of accumulating 0.000001410642 Monero per 8 hours, it would take me 3,762 years to reach the minimum withdrawal threshold of 0.05 Monero.
From my point of view you'll be better by using your Raspberry Pi for other ends, such as Pi-hole[2] for example ...
[1]
https://www.tomshardware.com/uk/how-to/mine-cryptocurrency-raspberry-pi[2]
https://pi-hole.net/Some technical insight to this arcticle. What the author is referring to as "bad shares" are actually stale shares.
It takes so long just to calculate 1 hash that the job can go stale before you finish, If that hash passes the difficulty
test the miner will submit it but it's too late.
The stratum errors were caused by the server timing out waiting for a share to be submitted. Normally a miner
should submit between 5 & 10 shares per minute. The stratum server times out after 5 minutes with no shares
submitted. Setting a lower difficulty can help but most pools use vardiff and will adjust the difficulty automatically,
within certain limits. If you can't lower the difficulty enough to submit shares regularly without stratum timeouts
then it's a complete waste of time, as the author concluded.
