Can I Give My Dog Little Remedies plain saline?

Yes, with care
Saline nasal drops (plain) is commonly referenced for dogs at published doses. Published guidance for dogs: 1-2 drops per nostril, every 8-12h. Plain saline only, no medicated sprays (oxymetazoline is toxic).
Source: Veterinary Partner (VIN)
Get the exact range for your dog's weight

Skip it or ask a vet first if

medicated nasal sprays (Afrin etc.)

The safe habit

Confirm any medication decision with your veterinarian, who knows your dog's health history and other medications. VetDose shows published reference data, not prescriptions.