White vinegar might be the best replacement for fabric softener
3 Ways To Level Up Your Laundry Game With White Vinegar – Grow Fragrance
9 Elements Vinegar 44-fl oz Fabric Softener Liquid in the Fabric Softeners department at Lowes.com
How to remove the vinegar smell from fabrics that were washed with vinegar and liquid detergent but not rinsed well before adding fabric softener - Quora
Can Vinegar Clean Clothes?: Learn the Answer with Our Guide - Marigold & Ivy