Google has removed Conversations_im from the Play Store

I'll phrase my issue differently: Is there any way to have reliable notification delivery that are time critical? Is actually calling the only 100% reliable option, as the PagerDuty does?

Fellow humans, there are alternatives to Google and Apple! Your neck need not be under anyone's boot! You don't even need to give up any functionality:

Data service:

The simplest thing is to buy a prepaid SIM and top it off with cash. The lovely people over at /r/nocontract maintain a big spreadsheet so you can filter by various properties of the available contracts.

Another way to go is to pay for a postpaid plan with a virtual credit card (VCC) like at privacy.com. It won't be linked to your name at the telco, but of course privacy.com knows who you are. There is also Abine Blur, and some others.

Yet a third way to go, which is nascent, is buy an eSIM with crypto. You can also buy prepaid VCCs with crypto.

An interesting new choice is PGPP https://invisv.com/pgpp/ who rotate your IMSI and do some other cool stuff. It works by e-sims.

All these methods make you /pseudo/nymous, but obviously you're still identifiable by subscriber number and possibly IMEI, to put aside correlational things like your traffic profile. You can help this problem by routing everything through a VPN. Then you're pseudonymous but the cell carrier knows nothing about you other than that you use a VPN. Pay for the VPN with crypto. Of course now the VPN provider knows your traffic, but you're much more anonymous to them than you are to a telco. You make your choices. Defense in depth. Etc.

OS:

GrapheneOS: https://grapheneos.org/ Very much like Calyx, but extra-hardened and with no MicroG. No involvement with Google at all by default. You can make a secondary profile in which you install Google Play Services to set up an environment where you can run unprivileged Play services + whatever crapware you need that requires them. Unprivileged here means it's like any other app: if you don't give it access to your location, it won't know where you are. If you end the profile session when you leave, Play Services stops running and stops talking to Google.

CalyxOS: https://calyxos.org/ Privacy-respecting Android distribution that replaces Google spyware with MicroG, so you can have your cake and eat it too. Most everything will work as you're used to, but it does still talk to Google to make that happen.

LineageOS: https://lineageos.org/ The successor to CyanogenMod, will work with many different phones. More privacy and control than stock Android.

There are also many others: Sailfish, Replicant, e

Hardware:

CalyxOS and GrapheneOS run best on Pixels. The path of least resistance is to get one of these phones and run GrapheneOS with Google Services installed in one profile or other.

You could also buy a Librem 5 https://puri.sm/products/librem-5/ If privacy and security and hacking are really important to you.

Or a pinephone: https://www.pine64.org/pinephone/

Neither work very well by regular standards, but they're cool :-)

Google even allows this for banking apps.

And yet the only reason Google won't add internet access as a revocable permission is their ad business.

Chrome constantly scans your harddrive in a way you can't easily turn off, and it's not for your safety: it's for the safety of their ad business to try to catch malware that engages in click fraud. If you have media or backup drives it just constantly adds wear to them.