In electronics and computer stores, look for PRF IPA Kontakt or AG Termopasty Kontakt cleaner; it's pure isopropyl alcohol. At least
liveshop.lv in Rīga sells it in a liter canister, which should last you years. There are several web shops who have it in spray form.
I use acetone, as it's cheap and easily available here. Use the pure stuff, as nail polish removers often have some kind of soap and scents. Check auto parts and paint stores. Got a half-liter bottle almost ten years ago, used for both electronics and removing heat sink compound from processors and heat sinks, and I've still got half of it left.
Acetone does not damage PCBs or the components, and is commonly used as a PCB cleaner. Just ventilate well, the fumes are not healthy.
(When I started using flux, and acetone with an old toothbrush to clean my "soldering" work, it made a huge difference in the results; looks half decent! Borrowing a saying from welders,
"flux and cleaning makes me the solderer I ain't".)