I would like to use tucked sheets rather than sleep sacks. Is there a significant difference in safety? Additionally, can tucked sheets still be used safely once baby is more active and rolling?

When considering type of bedding for baby, it is important to consider the following:
Ensure baby’s head & face remail uncovered, the base (mattress) is firm & flat & that baby is placed on back for sleep.

Whether you use tuck sheets or blankets ensure baby is not at risk of wriggling under bedding. 
https://rednose.org.au/article/safe-bedding-is-the-bedding-safe
https://rednose.org.au/article/sleep-baby-with-head-and-face-uncovered

Once baby is rolling, many families choose not to use bedding as often baby does not stay under bedding &/ may roll under bedding.
Sleeping bag is probably the safest option when baby is rolling, as they reduce the risk of baby getting head/face covered.