Is there a way to update to the latest PHD2 in SM? I'm running the latest SM release for Raspbian, but I'd like to update PHD2 which was bundled... Can someone clue me in on the strategy for how bundled packages are addressed? Thanks.

OK, no response yet, so I'll ask a slightly more specific question.
Does anyone know if the following PHD2 build/update procedure would give problems on a PI4 running SM OS 1.5? This (modified) procedure is basically described here:
github.com/OpenPHDGuiding/phd2/wiki/BuildingPHD2OnLinux

0. Install build tools:
sudo apt-get install packaging-dev

1. Install dependencies:
sudo apt-get install build-essential git cmake pkg-config libwxgtk3.0-dev \ wx-common wx3.0-i18n libindi-dev libnova-dev gettext zlib1g-dev libx11-dev \ libcurl4-gnutls-dev

2. Get the PHD2 sources & generate Makefiles
git clone github.com/OpenPHDGuiding/phd2.git
cd phd2
mkdir -p tmp
cd tmp
cmake ..

3. Build and install:
sudo make install

I'd like to avoid bricking my Pi4 and/or breaking PHD2. If folks (especially anyone who's built PHD2 on their PI) can advise, that would be greatly appreciated! Thanks....

You can backup your Pi’s SD card before and then try without risk.

I‘m asking me the same question and will give it a try with a current backup as a joker. In my case it‘s a bit more complicated since I run the Pi from a SSD (in combination with a SD card). Maybe a bit more work then in case I have to revert to my backup just in case...