From the photos this https://www.homepro.co.th/p/1160950 looks like it has a full steel frame so the top would just unscrew. There are similar items not branded as "desk" which are rather cheaper too.
https://globalhouse.co.th/Fillter/search/1?q=folding table
The frame would prevent any sag in the middle where most of your load would be. The 35cm overhang on each end would likely be OK but there's nothing to stop you adding a glued doubler underneath (you would have spare material from the top) which would add significant rigidity. Extending the steel frame would probably be outside your scope ????
The chipboard/Formica tops just aged, the Formica started to look tatty and the chipboard got the damp in, chipboard really doesn't like the damp.
I rounded off the edges with a router, but simply sanding off the sharp corners would serve.
Finish with a polyurethane stain of a colour to your liking and the job's a good un.
I'm not sure where one would get the material cut to size as I have the necessary kit to do the job. If you let us know where you are hopefully someone will have suggestions.