Which public extended key should I use? I'm trying to make sense of the information shown here and how the extended public keys work.
The web wallet I'm using only supports this derivation path m/44'/242'/0'/i', so if I understood correctly:
(1) It doesn't matter what the index for the coin is, the extended private and public keys should be the same for all coins, that's why the same seed words can be used for all coins in the HD wallet.
(2) Since the derivation path used on the web wallet has hardened derivation in some indices, the extended public key won't be able to generate the same addresses available on the web wallet.
Imagine I want to share a key with someone that would allow them to generate the same addresses available for my seed words on the web wallet, but without allowing them to send any transactions. Is that posible? Which derivation path and extended public key should I use? Say for instance for this random 24-word nemonic phrase:
guitar letter tuna oppose
mushroom affair sock adjust
couch plunge angry ladder
evolve dial only maximum
stereo drama final public
become manual pelican glue
Imagine I want to share a key with someone that would allow them to generate the same addresses available for my seed words on the web wallet, but without allowing them to send any transactions.

I'm pretty sure what you suggest is not possible.
The only single datum of information from which you can produce all the addresses is the one that also allows you to spend money.