You can't efile a return with all zeroes.  But maybe they won $2 on a scratch off ticket?  Or maybe there's $0.53 of interest in their Wells Fargo account.

You could go with "other income - to allow e-filing".  Or you could just paper file.  Or you could talk them out of doing something that isn't necessary.  Maybe tell them the IRS audits a lot of returns with no reported income these days 😜

same here, I put on line 21 other income, $1 entry as "de minimis for efling"

You might be catering to crazy people. On the other hand, they might have lots of income they don't want to tell you about, and they figure filing a return will avoid failure to file penalties if they get caught.  (Sometimes that works.)