word choice: data points or datapoints?

Solution 1:

Both forms are alright, but data point is much more common.

Regarding dictionaries, Lexico (based off of Oxford Dictionaries) lists datapoint as its head entry; Cambridge has data point in its corpus but not the other. Merriam-Webster has neither.

In media, "data point" is far more common (262 results in the Corpus of Contemporary American English) than "datapoint" (13 results). Even with an international corpus like NOW (News on the Web) "data point" appears 3168 times compared to 155 for "datapoint." Even in JSTOR (an academic database), "datapoint" appears 584 times to "data point"'s 22,876 times.

So while data point is much more common, both are attested, so the choice comes down to individual or publication preference.