Import GoPro Hero 7 4k30 HEVC footage resulting in audio only

Dear all,

I know there are numerous topics on the gopro and adobe forums, watched youtube tutorials. I have read a lot but I am still confused.

This week I bought a monthly adobe cc premiere pro plan. Installed version 13.02.

On our annual skiing trip I shot a lot of cool movies in 4k30 16:9 HEVC format. (file name of the videos similar to: GX010058.MP4). Now I want to edit all of these videos into a nice movie. If I am correct this version of premiere pro cc should be able to support HEVC files.

My main issue: if I import any GX......MP4 movie into premiere pro I only get audio into premiere pro.

My current editing rig is my dell laptop (8th gen i7 processor, 16gb ram).

On the web I see a lot of suggestions like: converting the movies upfront with handbrake. Or converting the movies with Adobe Media Encoder before starting to edit in premiere pro.

But I dont want to convert. Why is converting required? Is my understanding correct that, if you have the right sufficiently powerful editing rig, that converting would not be required?

My main issue with converting is: It takes a lot of time, and I am afraid to loose video quality in the converting process. To illustrate:

My understanding of HEVC is that it should be an "efficient way" of saving video files. So if I convert the HEVC H265 into H264 (high bitrate identical source), why are my H264 files much smaller than the h265 files. I can only draw one conclusion and that is that I am sacrificing on video quality (although I cannot immediately see any difference in quality).

Why can GoPro Quick application edit the HEVC Files immediately and is Premiere CC not able to import the files?

All of your feedback and suggestions are highly appreciated!