In both these sentences, what does でも mean? (I know the meaning of the sentences, just not the particles)

カードでもいいですか。
なごやでもうっていますか。

I know that で is a particle that can denote location or mean something like "by means of". I know that も is a particle that means too, either, etc. I also know that でも can mean but, but this doesn't seem to be the case.

Do both particles acquire different meanings or do they become some sort of particle themselves? Or do they simply retain their meanings, but combined have a different one?

Thank you!

P.S.: I do not know any kanji, hence I wrote in kana and hope you can too.

In both these sentences, what does でも mean? (I think I know the meaning of the sentences, just not the particles)

カードでもいいですか。
なごやでもうっていますか。

I know that で is a particle that can denote location or mean something like "by means of". I know that も is a particle that means too, either, etc. I also know that でも can mean but, but this doesn't seem to be the case.

Do both particles acquire different meanings or do they become some sort of particle themselves? Or do they simply retain their meanings, but combined have a different one?

Thank you!

P.S.: I do not know any kanji, hence I wrote in kana and hope you can too.