If I have apps synced between my phone and laptop
Unless you have an Android laptop, you can only back up Android apps on your laptop.
is it possible to get malware on my laptop if I download/open something on android phone?
If it's not an Android laptop, you can't open it (as in run it) on the laptop. There are viruses that are transmitted via email, and they can be transferred that way, but I don't think anyone would put a Windows virus into an Android app.
My Gmail & Firefox are synced. Android seems somewhat immune.
Android is as immune t viruses as Windows is - IOW, not t all. As I said, email can carry viruses (and other things like phishing). Firefox addons can also carry viruses. Going to a website can download Javascript that can download a virus.
My worry is that by opening something in Gmail that contains a trojan could it be synced to my laptop?
No,m it won't be synced. If the email has an Android virus, opening it in your phone will put a virus on the phone. If it has a Windows virus, opening it in your laptop will put a virus in your laptop.
Same thing. It's not syncing that does it. To Android, a Windows virus isn't a virus, it's just a bunch of data. There's no reason it would get sent to the laptop. (You don't sync the entire memory of the phone in Firefox, you sync bookmarks, open pages, passwords, etc. They don't have viruses, they're text.)
You should still be running antivirus, antimalware and anti-adware on both the phone and the laptop.
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