Just sharing my experience for Iceland, travelled in March 2023, which was supposed to be the end of winter but was met with heavy snowfall (no snow 2 weeks before the trip but it suddenly just snowed for 10 days straight according to a local).

12 nights trip in Iceland (Ring Road + Golden Circle) including 2 short day trips on my layover at Helsinki, Finland.

KL - SINGAPORE - HELSINKI - REYKJAVIK - VIK - SKAFTAFELL/Öræfi - Egilsstadir - Mývatn - Akureyri - Snæfellsnes Peninsula - Golden Circle - Grindavik (think this place is closed now)

Spend a total of 25k all in including flights, food, tax, petrol etc. for 2 persons, about 12,500 per pax.

Weather in Iceland is unpredictable, good to download some apps like Faerd & Vedur and Safetravel, which gives updates on things like road openings/closing. Driving in the winter in Iceland is relatively safe compared to other winter countries as traffic isn't heavy and as long you take it slow you are fine (The locals and Europeans drive really quickly though just let them pass). However if the snow is too thick don't drive through it, would be good if you can get hold of a shovel and a brush sort of snow scraper to clear your windshield in the morning.

Food is not cheap in Iceland, recommended to eat less vegetables and fruits as they are imported. Instead just eat lamb and meats. Best place to shop imo is Bonus.

Make sure you have a credit card, as its virtually the only form of payment, many places dont take cash.

Another dodgy aspect is parking, these icelandic really invested in a good camera system which records the cars entering and exiting the parking lot of an attraction and you are expected to make payment at a machine, even if you did not stop, they consider you as already entered the place and will send you a bill.

Vaðlaheiðargöng tunnel near Akureyri is the only tolled road in Iceland, just remember to make payment online after using it.