I often "rescue" discount plants that have either been neglected or are perennials past their prime but every single plant gets inspected and if I have any qualms it doesn't come anywhere near my yard, nevermind inside my house. It's simply to difficult to effectively quarantine While giving a plant the airflow, moisture and light it needs. If you are determined to quarantine, keep it in your bathroom and Don't touch it.
I will say in my first 20 years as a houseplant gardener I often believed I had infestations or fungus problems.. and sometimes I did, but since I've gotten good at this, I have to say in the last 10 years I have had few to none. I suspect that at least half the time (if not 90%)I suspected an insect or microbial culprit it was actually care deficiencies. We always think that that because we are following good advice and "the rules"It must be some external parasite we brought into our otherwise pristine homes, and that's simply not the case.
I don't quarantine anything. All my plants go outside every summer and come in every fall, and yes, I get bugs, but almost never ones that are bad for my plants. I might be lucky that I'm not afraid of most bugs... their itty bitty babies just trying to survive and balancing our ecosystem, living with my plants and they tend to stay in their pots.
I did buy a bottle of systemic pesticide many years ago, and I have a spray bottle of neem oil. I Am glad I have these on hand, I have the same bottles and maybe used them twice in the last 5 years, mostly as a prophylactic. It was very helpful for piece of mind and to approach things in the sense that I can be confident if something looks bad, I don't have the balance right..and not to look for zebras when I heard hoof beats.
