There are some decent online undergrad degrees nowadays, but when I look at graduate programs they tend to want letters of recommendation and many prefer at least some from academic sources.
But if you’ve completed you’re undergrad degree in an online program, you’re not likely to have built any significant relationship with any professors, at least not in a way they’d be comfortable recommending you.
Are online undergrad programs just no good if you want to be able to consider further education or am I missing something?
A lot of students will have relevant internships or work experience -- this definitely would make for a great recommendation letter!
If you're pursuing a PhD, it would be ideal to have some undergrad research experience. I assume you'd pursue this online similarly to in person -- taking an interest in a professor's work and reaching out. Or over the summer, there are jobs at national labs and plenty of undergrad research experience summer programs.