One of my side businesses is https://icryptonode.com/ that sells monero-specific hardware and software. Monero is even clunkier to user than Bitcoin for a bunch of reasons, but over the years has been getting easier.

Unfortunately, a lot of the ways to make it easier (remote nodes, fully-synced transaction history by a cloud service) severely curtail the privacy element. But it still makes it easier to invest and transact in, if you aren't super worried about privacy.

All being said, I love Monero, and its community is exceptional. If you go to DEFCON in Las Vegas, be sure to visit the Monero room!

The Feds archive all encrypted communication, including supposedly untraceable Monero ring signatures, so that they can decrypt it sometime in the future when they have (and they will at some point) a strong enough quantum or a cryptanalytic exploit. It may be safe enough for pragmatic reasons to want secrecy like selling drugs, but if you want secrecy for philosophical reasons then you should know that even Monero won't really give you it.

No privacy is perfect. Monero is evolving. It’s state of the art currently.

Does Monero have a upper limit of issued coins like Bitcoin?

It doesn't. I see here https://www.coingecko.com/en/coins/monero

Circulating Supply: 17,630,237 / ∞

It drains to a trickle and then continues indefinitely. The supply is less than bitcoins until 2040.

Still, like Bitcoin, the vast majority of all Monero emitted in the first century, is emitted in the first few years. Grin has the simplest possible emission, at 1 Grin per second forever. They're all disinflationary, i.e. the yearly inflation rate goes down to 0.

No, but Zcash does