It appears that Vitamin D oil drops are just as effective as tablets. Well they have the oil which helps the Vitamin D absorb since D is fat soluble I guess. https://vitamindwiki.com/tiki-download_wiki_attachment.php?attId=13764&download=y
compared the effectiveness of tablets versus oil in raising S-25-hydroxyvitaminD(S-25-OHD) in plasma
by re-analyzing data from a previously performed observational study in which immunodeficient
patients with S-25-OHD concentrations <75 nmol/L were randomly prescribed vitamin D tablets
(1600 IU/day) or vitamin D oil-drops (1500 IU/day) for twelve months. Tablets and oil were compared
for the effect on S-25-OHD concentrations after 3–5 months and antibiotic use. Results: Data on
S-25-OHD after 3 months was available for 137 patients treated with tablets and 69 with oil drops.
Both groups exhibited a significant increase in S-25-OHD—oil-drops from 55 to 86 nmol/L and tablets
from 52 to 87 nmol/L—with no difference between groups (p = 0.77).
"Are Vitamin D Tablets and Oil Drops Equally
Eective in Raising S-25-Hydroxyvitamin D
Concentrations? A Post-Hoc Analysis of an
Observational Study on Immunodeficient Patients", Nutrients, published April, 2020.