Mullvad has a 30-day money back guarantee.

Apart from that, some payment methods (like crypto) allow transmitting arbitrary amounts. At least, paying for years in advance works without issue. You could pay a few cents and try it out, but be mindful of fees.

Almost all extensions will weaken your security posture. In fact off the top of my head there are basically only two kinds of extensions that could improve it:

• ad blockers
• (maybe!) password manager integrations

Anything else is questionable at best. Maybe you could create browser profiles where you install extensions somewhat more liberally, with decreased expectation of safety.

According to my mom, the calcium off her teeth.

“My dentition was so great, but then you came.”