TL;DR (Too Long; Don't Read)
There are -- if you will -- two (2) versions of Android:
(a)
Android OS
(b)
Android TV OS
Android phones & tablets always use (a). In order words -- Android phones & tablets never use (b).
Some Android TVs / TV boxes use (a) -- while more (& more) newer Android TVs / TV boxes use (b).
DO NOT ASK ME WHY THEY COME OUT w/ two (2) versions of Android.
Go ask Google. Haha..
If your phone / tablet / TV / TV box runs (a) -- you should be able to find & install MeWatch from the Google Play store

(This is provided your TV / TV box that runs (a) has Google Play store bulit-in.)
The problem is..
MeWatch app -- which was previously Toggle app --
all along officially never support (b) Android TV OS !!
Since MeWatch don't support (b) i.e. Android TV OS...
So if your Android TV or TV box runs (b),
you'll not be able to find MeWatch in the Play store on your TV that runs (b) !!
DO NOT ASK ME WHY MeWatch only supports (a) Android OS --
but don't support (b) Android TV OS.
Go ask Mediacorp. Haha...
As far as I know (AFAIK),
Mediacorp expects/thinks that any TV (or TV box) that runs (b) Android TV OS -- will have Google Chomecast bulit-in...
So if your TV runs (b) -- then
officially Mediacorp expects you to install MeWatch on your phone & Chromecast to your TV that runs (b).
Nowadays in Singapore --
99.9% of people looking to buy a new Android TV -- wants the new TV to be 4K Netflix certified.
The
"problem" is..
All 4K Netflix certified Android TVs --
always run (b) Android TV OS --
which is NOT SUPPORTED by MeWatch !!
Then subsequently after buying the new TV that runs (b) ...
The question "Why can't I find or install MeWatch from Playstore?" -- will appear again (& again & again)... Haha..
Also,
if someone who never bought a TV box before asks for a TV box recommendation --
MORE THAN 90% of the time people will recommend Xiaomi Mi Box S.
But Xiaomi Mi Box S TV box also runs (b) Android TV OS --
which is NOT SUPPORTED by MeWatch !!
Then subsequently after buying the new Xiaomi Mi Box S that runs (b) ...
The question "Why can't I find or install MeWatch from Playstore?" -- will appear again (& again & again)... Haha..
If you want to watch Mediacorp stuff on your TV --
but don't wish to Chromecast from your phone/tablet:
(1)
Go buy a new Apple TV !! (MeWatch is officially supported on Apple TV

)
(2) Watch Mediacorp Live TV channels via (free-to-air) DVB-T2 broadcasts.
(1) can access both Mediacorp Live TV & VOD contents.
(2) can only access Mediacorp Live TV.
There is always an option (3) -- totally don't watch any Mediacorp stuff at all
If you give up watching any Mediacorp stuff (both Live TV & VOD contents) -- you no need to worry about casting from phone or whether MeWatch can be installed/used on your Android TV (or TV box).
Hope the above helps.