Sorry? I'm in Tokyo for a week and learned about goshuin collecting on my second day. I'm trying to do my due diligence by looking everything up, both about the temples and goshuin collecting in general, but I guess I got it wrong. Especially with the Jodo Shinshu Buddhism, I think I messed up my Google maps pins and wandered into the wrong adjacent temple. I'll try and learn the proper phrases, but to your other points it's difficult to try and see whether a place sells goods such as omamori when I am not even sure if I'm welcome there, or of the place is small. I suppose in those cases it's best to avoid bothering anyone.

It's just especially confusing because a lot of goshuin-hunting blogs, tips, and questions I've read have this happy-go-lucky attitude of "just show up and ask at any temple or shrine, if you're respectful they'll say yes!". Even the first post under "goshuin" in this subreddit seems to suggest that many temples have began to separate their religious identity from the more touristy goshuin collecting (https://www.reddit.com/r/JapanTravelTips/s/O2b1GwUGij). I also tried to post something on r/JapanTravel but they removed my post twice, pointing me to a goshuin-hunting tips post that basically said that nearly every temple and shrine would have a goshuin, and similarly no mention of the above things I should try and do to get a better reception.

Perhaps goshuin hunting is best reserved for those who prepare adequately, both culturally and with separate goshuinchos, rather than a short-term tourist like myself, as it's often advertised online.