According to this bogleheads write-up (Link), if you invest in non-US domiciled ETF and are neither US citizen, US green card holder nor US tax resident, then you may not be subjected to US Estate Tax for holdings over $60,000. However, there is a big caveat: your broker cannot be US based. Otherwise, you will still be limited to the $60,000 holdings where the US Estate Tax will still apply to anything over that.
So if you plan to have more than $60,000 invested, perhaps it will be better to find other brokers which are non-US based. Or, perhaps with in-depth knowledge of the intricacy of US taxation system and proper planning, there are certain steps that can be taken to repatriate your monies back to Malaysia soil while avoiding detection in the event of an unexpected death.  ¯\_(ツ)_/¯

Hmm, I am a little on the younger side, so I'm not sure how valid my opinion is, or perhaps people would think less of me for being on the paranoid side, but I'll share it anyway.

First of all, I invest primarily in VWRA, an Irish-domiciled ETF. I will never have an holding of more than 60k in US stocks/ETF/cash in my IBKR account so I shouldn't be liable for any US estate tax concerns.
I've told my close family that I have foreign investment, and that in the event of my demise, they are free to help themselves to it, at least I would have paid for my own funeral.

As a backup plan, I've also prepared a document detailing my access info, screenshots of how to liquidate my portfolio, my withdrawal routes, as well as instructions on how to contact IBKR for assistance should they are unable to or unwilling to pretend to be me and access my funds. Of course, there's always an option to proceed with my will and death certificate to access it legally - if it does come to this, and they find it worth the trouble.

The document is then stored in an encrypted volume requiring PASSWORD_A, attached to my gmail on scheduled send in 6 months, and also stored in a physical thumbdrive, mentions that password will be emailed in 1 month.
Then in another gmail account, PASSWORD_A is also on scheduled send in 7 months.
Then, I set an reminder to myself to renew the send date every 5 or so months to keep it from sending out until I die, acting like a dead man's switch.

This should keep my access detail safe even if I made a mistake now and then (e.g. forget to renew encrypted volume send date), stolen, or my relationship with my family deteriorates in the future.

If it sounds mega paranoid, it is. I am a selfish person and my benefits should always comes first above all else. I wouldn't trust a second soul to access any of my finances as long I am still alive. I've seen enough bad story regarding family and money as it is.

TL;DR: Family is aware of where I am invested, will have access to my investment as soon as my death certificate is issued, or in 7 months as a backup.

So IBKR (UK) means I am not subject to US estate tax? (I transferred in from Tradestation Global.)