Any recommendations for 80 plus yr old what kind of portable breathing machine will be safe in case oxygen drops below 90 and ambulance can come in. i saw some nebulizer machines on amazon. will those help to breath over 90 % oxygen?

You want a real Dr/resp therapist to see your 80+ person and evaluate and make recommendations. Not Dr Amazon or any other Dr. who has not seen and examined he or she.

If you have access to portable oxygen for your home, this may be prescribed by your physician. Home services usually set up the equipment. COVID 19 and flu vaccination for all household members 6 months of age or older Nebulizers are used to deliver inhaled medication.