A few options I know of:
1. Use a US address to open a US brokerage (family, trusted friends, etc.) - reports vary of if this ever really matters, probably depends on the brokerage
2. Buy EU UCITS ETFs inside a Roth IRA - outside an IRA, they're PFICs and pretty toxic. Inside an IRA, doesn't matter, there's no tax or reporting. Interactive Brokers definitely allows this, I did it a couple weeks ago.
3. Buy options on US ETFs and then exercise them to get the underlying. Silly workaround to PRIPS, but I've heard it work from multiple people. You do have to buy in big chunks (100 shares at a time), and its a faff.
4. If you aren't already using your UK pension/SIPP, you won't be able to buy US ETFs but hopefully have some decent fund options there, and it's well protected by the tax treaty, no worries about PFICs.
5. Individual stocks - much more of a hassle, much harder to be diversified, but avoids both PFIC and PRIPS issues. Can be done inside an ISA (probably at Hargreaves Lansdown or Interactive Brokers, not many brokers will take a US citizen), or a taxable account (US or UK based, won't change the tax).
6. Become an accredited investor, with €500k+, history of active trading, and/or employment in finance (need 2 of the 3). Interactive Brokers again supports this, if you qualify. The PRIPS/KID rules only apply to retail investors, not accredited investors.
None of the options are ideal, but those are all the ones I'm aware of. I personally use a combination of my UK workplace pension, Roth IRA, and individual stocks in my ISA.