This issue is applicable to Georgian.

Dedicated mtavruli Unicode characters were only introduced in Unicode v11 (2018). Prior to that, authors had to use special fonts with the mkhedruli code points in order to write mtavruli letters, and CSS text-transforms (ie. to uppercase) had no effect. Unicode 11 introduced not just the new characters, but also mappings from mkhedruli (lowercase) to mtavruli (uppercase).

Note that Mtavruli is only used for ALL CAPS typography, and is not used at the beginning of a sentence or for proper nouns.

Tests & results:
interactive test, Fonts display characters needed for modern Georgian text

This test includes all characters used for Mkhedruli and Mtravruli in modern Georgian (source) and has been tested on macOS and Windows10. To run the test, open the link on each platform, click on the F icon, top left, and mouse over the pre-installed font names listed for the appropriate platform.

Test passes if you see no tofu.

The results for macOS 12.2.1 are as follows:
Menlo ✅ Helvetica ✅ Helvetica Neue ✅ (Arial Unicode MS ❌)

Results for Windows10
Segoe UI ✅ Calibri ✅ Sylfaen ❌

MacOS Catalina and iOS 13 introduced support for Georgian uppercase letters using updated Helvetica (2019).

Microsoft added new Mtavruli characters to their Calibri (version 6.32) font on the Windows 10 October 2018 Update 1809 and to Segoe UI (version 5.62) on the Windows 10 May 2019 Update 1903.

Google updated Noto Georgian fonts to cover Georgian Extended characters. These fonts are not included in Android 10, but they are already used by Manjaro Linux (Arch Linux), which has latest glibc libraries, so Mtavruli is fully supported there and Georgian capital letters can be typed using Caps Lock.

Support for Arial New Unicode was discontinued some time ago by Microsoft, so it is likely that any content relying on that font won't include Mtavruli characters anyway.

Priority:
When first raised this issue was marked as basic. Given the new support added to various pre-installed fonts on Mac and Windows and the other platforms mentioned, the priority is reduced to advanced.