Singapore food cheaper. Can get SGD4 per meal at Food court. But comparison is dollar to dollar.
Singapore no need car/motorcycle.
If you have kept SGD, have a property already to live in SG, then it is indeed cheaper in Singapore.
If no SGD and no property, now only convert MYR to SGD to go for cheaper living expenses, sure die. Conversion rate will make you pokai in Singapore also.

If have SGD and SG property, might as well convert to MYR and live like a king in Msia kampung. Just use bicycle.

Retirement means different things to different people.
For some, still need to work, part time maybe like Grab.
For some, means enjoy life, go overseas trip like 4x a year.
For some, weekend fine dining.
For some, drive around and go places in Msia, foodie hunting. Cuti Cuti Malaysia.
Pick up hobby like carpentry or drawing also need money.

The amount needed varies from person to person, locality to locality.
EPF only states the minimum requirements for most people.
If you are outlier (high end side), then work on it to get more $$ before retire lor.

I read before, to retire need 3 things:
1. Health
2. Wealth
3. Three hobbies.

Oh, BTW, Roti Canai I remember used to be 30 cents. Now oledi RM1.50.
So inflation is real.
Government is printing money all the time.
So save money only sure kena inflation loss kaw kaw.
Need money market.
This is where the rich gets richer and poor gets poorer.

Do your maths properly. And need safety margin. Kena another few 1MDB, drop to B40 easily.

Working time hobby is work 8 to 5, OT work, part time work. Especially in younger days.
Save the money and invest.