The smallest you can open I think is around 150k, at least from the predefined in Alby Hub. Yesterday I opened an extra one with 500k because I wanted redundancy and a connection within Europe to have faster connection time to me. You can browse a lightning map and see which big nodes are around you and then copy their public key. What I did was to find a few, put their public key in Alby Hub and try to open a very small channel like 50k sats. Then the channel either opens or fails mentioning the minimum size they accept.
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