I think the reason for this is because of cakepay. When you compile the code of cake wallet, it does not include the keys to allow for instant payments for cakepay. The compiled version does contain the official keys to allow instant payments for cakepay. These keys used for instant cakepay payments is to prevent double spend attacks for cakepay.
That being said, sadly no one can truly verify the app.
However the benefits of having your own repo is faster updates which is useful when a coin has a hard fork update. Official F-Droid repo apps updates could take days to be released. And if you can build the app from source and it matches the checksum of the fdroid release, all is good.
I dont see any issue with the user choosing weather upvotes or downvotes are visible or not. Not in favor of moderators or admins having a choice on this matter.
Graphene is the best option but lineageos is also good and covers many devices. The con of lineageos is the lack of hardened security which graphene provides.
The easiest way for most people is a kyc exchange like Kraken. LocalMonero is better as long you buy from someone who does not require kyc and the best forms of payment is cash by mail or cash using an atm if your in Australia.
There is also buying bitcoin or litecoin at a crypto atm and swapping the btc/ltc for xmr on a swap service like changenow
I also recommend forgejo. They are also working on adding a federation feature to forgejo just like Lemmy has!