Help needed with phone video sync

This has been driving me crazy for months. I'm trying to sync video from a Galaxy A35 phone with audio recorded through reaper. I know the sample rates need to match and I've tried converting the video to 30 fps since this phone will only record in variable frame rate as far as I can tell.

For the audio I'm running a mic into an Audient iD14 that is getting the clock from an ultragain through the optical ADAT connection. Then going into the pc via usb.

Here are my notes from some tests I've been doing today to try to finally get this figured out:

Test 1

project sample rate - 44.1

(project sample rate box checked)

audio device sample rate - 44.1

(request sample rate checked, allow projects to override device sample rate checked)

ultragain sample rate - 44.1, master

video audio automatically resampled to 44.1 on import into reaper

-video behind by about .04 sec after 5 minutes

Test 2

project sample rate - 48

(project sample rate box checked)

audio device sample rate - 48

(request sample rate checked, allow projects to override device sample rate checked)

ultragain sample rate - 48, master

video audio not resampled on import

-video behind by .02 sec after 5 minutes

THEN:

test 2 video put into Shotcut and converted to 30 fps.

-no difference in sync (maybe a few frames off from the original video) except new video now starts about .01s earlier to achieve proper sync at the first clap and ends about .05s earlier than the original video's audio

I was hoping that matching sample rates and converting the fps to 30 fps (which is what the reaper video setting is set to in "project settings") would fix this issue.

Am I missing something here? Would really appreciate any thoughts or troubleshooting tips. Thanks in advance!!