Misc/Decent Usable Android Flip Phone
This flip phone works pretty well.

It's Schok Volt Flip Model SC3218. I purchased it in 07 of 2026 from a local best buy.
The phone has a few great features which allow it do to most things other phones can
It runs Android 8.0, making it compatible with Tailscale. Android 8 contains the androidx.security:security-crypto library which some apps rely on now.
Developer Mode can be enabled
ADB Debugging can be enabled
Sideloading APKs is allowed
How to enable developer options
Open the "Tools and Settings" app
Click "Lock Control 2.0"
Click "System Control"
Click "Allow developer mode". While you are here, enable the Virtual Mouse if you haven't already
Developer mode can then be enabled from the system settings by clicking the build number of the device 10 or so times until the developer options appear.
How to enable ADB Debugging
Enter the developer options to turn it one.
Ensure the USB settings are set to MTP
Use a data compatible USB-C cable to test ADB. Some users report that their phones are locked at "Charging Only" in the settings. I experienced this too and found that it was because my charger was a charge only cable. That was why it perceptibly looked like the option was locked in my case.
How to install APKs
Use ADB and install armeabi-v7a Android 8.0 APKS.
I had success installing some with the file manager and some with ADB from a PC. If the ADB command ever freezes then it indicates something about the application does not work with this phone. I know this phone is missing some media codecs which make some applications like "scrcpy"
Here is a list of applications that I've installed. You can copy the name of each program to find an APK online. I downloaded most of them from F-Droid and some of them from apkmirror.com.
The name of "QRCodeGenerator-de.t_dankworth.secscanqr_21.apk" would be "de.t_dankworth.secscanqr_21.apk"
PhotoViewer-gallery-396-proprietary-release.apk
Wikipedia-org.wikipedia_50594.apk
QRCodeGenerator-de.t_dankworth.secscanqr_21.apk
DeviceHWInfo-ru.andr7e.deviceinfohw_5.23.1-234_minAPI15(nodpi)_apkmirror.com.apk
TextEditor-com.rk.xededitor_98.apk
AppManager-io.github.muntashirakon.AppManager_450.apk
EmailClient-org.dystopia.email_121.apk
ShareVIAHTTPcom.MarcosDiez.shareviahttp_39.apk
Dictionary-io.github.yamin8000.owl_57.apk
ShareToClipBoard-com.tengu.sharetoclipboard_30.apk
MPV-is.xyz.mpv_46.apk
OrganicMaps-app.organicmaps_26072306.apk
SimpleHTTPServer-net.basov.lws.fdroid_70000.apk
RSSReader-de.lolo.rssreader_157.apk
APKMirror-com.apkmirror.helper.prod_2.0.3_(41-d04e542)-41_minAPI23(arm64-v8a,armeabi-v7a,x86,x86_64)(nodpi).apk
AppKiller-superfreeze.tool.android_1001.apk
FileManager-me.zhanghai.android.files_39.apk
FTPSFTPServer-org.primftpd_71.apk
Termux-com.termux_1022.apk