By "any degree" i mean nudists only when they're alone, not wear clothes when they get a surprise visit but do wear them when they know someone is coming, be always naked at home, or be always naked at long as it is allowed or in places when they won't get caught.
If possible, give your reasons as to why you think that.
Mondstadt: I think primarily Lisa and only on and off. I don’t see Amber, Jean, Sucrose, Kaeya, Diluc, Albedo or Eula really being nudist. Mona is a plausible one. Venti if he was drunk enough yeah. Fischl is a no as is Bennett. Actually looking now I can see Razor probably would’ve for a while.
Liyue: I can see Cloud Retainer for sure if she remained to her human form but would hide it within her adeptus abode and take dips into the water. Yelan I don’t think would care to. Ningguang I think she wouldn’t mind but wouldn’t want to. Zhongli and Hu Tao I don’t think would want to. Childe I don’t see it, really obsessed with being stylish with his weapons. Yun Jin, I just doubt. Shenhe I could see, Ganyu no, Keqing plausibly if she was an exhibitionist which I could see her being. Xiao no. Yanfei no. Beidou if she was alone on the alcor yeah. Baizu would be a hard no.
Inazuma: Thoma I’m split. Kujou Sara yes under extreme circumstances, Kokomi I don’t see it. Ayato I can definitely see him being a nudist, Ayaka not so much. Ei definitely not after seeing how flustered she got to losing from Yae in cards. Yae I could see her doing it freely without care even in front of shrine maidens. Gorou, sadly no. Arataki Itto, the one and Oni I gotta say no on. Kuki Shinobu I think would be fine with it but would be turned away from it with the rest of the gang annoying her into not doing it. Kirara I think would pass a fair bit too.
Sumeru: alhaitham would pass big time on it. Kaveh is a passer too. Dehya I could see as also Candace. Collei is a no I doubt she ever would. Nilou yeah I can see being so. Cyno would end up passing unless it was over something of TCG
Now for some honorable mentions: Ying’er definitely, Jeht is a likely, Babel would’ve been a yes she radiated to me Satsuki Kiruyin energy, Rana no but I’d be happy with her being one, Haniyyah (pink haired sumeru woman who was in the pokemon-like event who was hellbent on killing all mushrooms) I could see her maybe being so when out in nature.
Final mentions include Klee, Diona, Sayu, Qiqi, YaoYao if you say they would well fbi has your signal now. If I missed any then let me know
Edit: I ended up missing Yoimiya, Xingqiu, Scaramouche, Bennett, Chongyun, Heizou, Xinyan, Rosaria, noelle and Barbara (also Nahida for the fbi list)
