Please add square full stop like this as OpenType feature

This would be a very subtle, but nice idea!
I _think_ that what you're asking for is square-shaped (or at least rectangle-shaped) punctuation. Inter contains hundreds of different glyphs that uses "dots" and "stop-like" shapes. The style of Inter is to use discs rather than rectangles for this, so what you are asking for is a pretty big deal — a change to the style and personality of the typeface.
This will probably not happen, but I will keep this request around for the future.
Yeah it's also on i, !, ? and many more places, I'd merge this with the Helvetica R :) (couldn't find it anymore)
Yeah, Inter almost equals Helvetica, so needs square-shaped punctuation
Yes, in my opinion, Inter has many good alternates, and it's almost like the swiss army knife of open sourced sans fonts. It can be put in as alternates, and if someone doesn't want them, they don't have to see them, although it'll definitely be a pain if you want to make stuff like cvXX features, as you'll have to individually make each character again.
@rsms, If someone were to make squared shaped punctuation for Inter as stylistic alternates, and they would include it in a pull request, would you include it?
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I _think_ that what you're asking for is square-shaped (or at least rectangle-shaped) punctuation. Inter contains hundreds of different glyphs that uses "dots" and "stop-like" shapes. The style of Inter is to use discs rather than rectangles for this, so what you are asking for is a pretty big deal — a change to the style and personality of the typeface.
This will probably not happen, but I will keep this request around for the future.