One question: Is there also a suitable housing to mount the microphone on the camera? I would use the mic that I can put on my SLR.

Question

Answer

SmallRig (https://www.smallrig.com.de/search?type=product&q=gopro*) offers a whole range of cages for GoPros, which come with such mounts or can be ordered with them. I've had a very good experience with their products so far.

Answer

Versuche es hier

Direkt im Ulanzi Shop:
https://www.ulanzi.com/products/v2-protective-housing-case-ulanzi

Über Amazon

Gopro 7
https://www.amazon.de/Vlogging-Tasche-Handheld-Schutzgeh%C3%A4use-Vlogging-Rahmen-K%C3%A4fighalterung-Kaltschuh-Adapter/dp/B07P2L51LW/ref=sr_1_4?__mk_de_DE=%C3%85M%C3%85%C5%BD%C3%95%C3%91&keywords=Ulanzi+gopro+7&qid=1583357137&sr=8-4

GoPro 8
https://www.amazon.de/ULANZI-Multifunktionale-Action-Kamera-Schutzh%C3%BClle-Blitzschuhhalterung-LED-Videoleuchte/dp/B07N384VQ7/ref=pd_sbs_200_1/262-3514083-8715118?_encoding=UTF8&pd_rd_i=B07N384VQ7&pd_rd_r=9c53de12-b513-4210-b197-577fe4516020&pd_rd_w=AS39d&pd_rd_wg=yjbQ8&pf_rd_p=c8718c55-fb13-473f-a41c-592a17ad3468&pf_rd_r=4N8WGQDP441X9XKJFXMQ&psc=1&refRID=4N8WGQDP441X9XKJFXMQ

Answer

YES, there are various third-party aluminium housings online. Unfortunately, they all have the same problem: the adapter dangles around somewhere and has to be fixed somewhere with the help of adhesive Velcro strips, for example. Unfortunately, they haven't thought much about that. 
Unfortunately, Digitec doesn't have these housings, as far as I know. Just type "Kupton Protective Case for GoPro Hero 7 /Hero 6 /Hero 5/ Hero 2018" into Google - that's just one of several products. They come with a "slide" like the one on your DSLR, which allows you to mount the microphone perfectly.

Important: Due to the large angle of the Gopro and the small design, when using a "deadcat", make sure that you trim it a little... otherwise you will always see the hair in the picture :).

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Question about GoPro Per 3.5mm microphone adapter

One question: Is there also a suitable housing to mount the microphone on the camera? I would use the mic that I can put on my SLR.

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