I use their "Advanced" billing mode which is usage-based and ended up cheaper than the fixed-price "Simple" mode. This was my bill for last month (received ~300 emails):
Total: $0.35
Storage (GB/month): 0.00 ($0.00)
Emails sent to non-Purelymail accounts: 19 ($0.00)
Emails sent: 19 ($0.00)
Emails sent (GB): 0.00 ($0.00)
Yearly account fee (days): 30 ($0.33)
Shared-domain user fees: $0.02
They don't actually support wildcards, but there's a matching pattern "Any address starting with" for which I just entered "evidlo".
"Subaddressing allows you to tag the email addresses you give out. […] This also works with example_tagged@purelymail.com (in fact, everything after the first symbol- anything not a letter- in an address is ignored for routing) […]"
It's a standard, but it also makes figuring out your canonical address easy, which is great for ad tracking via sharing the hash of the canonical address easy. (They say they never share your address, but they don't say anything about a hash of it using the algo agreed upon industry-wide...)
Migadu allowed me to use - instead, so firstname-*@ also ends up in my inbox (firstname@).